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JUNIO 
PLANE 


BYEDWINM 
LOVE 


ALBERT 

WHITMAN 

^.COMPANY 

CHICAGO- 










'Tino 

.jL g 


Copyright, 1933, by Albert Whitman ^ Company 


^ 5 , 7S 


Printed in the U. S. A. 


NOV 15 1933 

*- * I 

©eiA‘ 67156 








'v‘nC ' 


FOREWORD 


^ Twenty'two planes are described in this book. All of 
1 ^ 5 ^ them have been built and flown, and all of them have proved 
themselves to be good performers. 

To build one of these models, it is necessary only to 
read the chapter telling about it, as the descriptions are 
complete for each one. However, some points are covered 
more fully in one article than in another; and if more infop 
mation is wanted on the carving of a propeller or the bend' 
ing of a shaft, a glance at the drawings for some of the 
other models will give the needed help. 

Although regular airplane model supplies have been 
specified, there are substitutes that are much cheaper, and 
just as satisfactory. For instance, instead of the rather 
expensive papers ordinarily used, wrapping tissue, costing 
one'twentieth as much, may be purchased; and as to am' 
broid, or other glues, a home'made cement is equally good. 
Simply get scraps of old celluloid automobile side'curtain 
lights, obtainable at any wrecking yard for ten cents a 
pound, and dissolve a few pieces in a pint of acetone, cost' 


ing thirty'five cents. Pour the acetone into a convenient 
bottle, add the celluloid, and let stand for a few hours, 
occasionally turning the bottle upside down to help in mix¬ 
ing. The same glue, when thinned, makes good wing dope. 

In building these models, remember that air friction 
slows up a flight, and consequently reduces duration. If 
spars and struts are streamlined, cind sanded smooth; and 
if the paper is tightly stretched, the ciir will flow past with¬ 
out much eddying, giving the best possible flight. 


Dedicated to my little boys, John and James, who 
all too soon will be old enough to build these planes. 


Edwin M. Love 


CONTENTS 


PART 1 
GLIDERS 

Subject Page 

1. The Midget Balsa Sailplane ....... 11 

2. A ThreeToot Balsa Glider.16 

3. A Convertible Glider.21 

4. Building a SixToot Sailplane ..25 

PART 2 

STICK MONOPLANES 

1. The Rough and Ready Tractor.33 

2. The Tumble Bug.38 

3. A Hydroplane Tractor.43 

4. The Flying Feather Tractor.. . 48 

5. The Mayfly Indoor Tractor ....... 53 

6. An Endurance Stick Model . . . . . . .58 

7. A Braced'Wing Monoplane.64 

8. A Twin'Pusher Plane . ....... 70 












CONTENTS—Continued 
PART 3 

FUSELAGE MONOPLANES 


1. A PushTull Scientific Model Monoplane . . . .78 

2. The Teeny Weeny Monoplane.84 

3. A Fuselage Low'Wing Monoplane.91 

4. The Seagull Tractor.97 

5. The Diamond Fuselage R. O. G. Plane ..... 107 

6. An R. O. G. Baby Commercial Plane.117 

7. Building the Freighter.126 

8. An Endurance Tube Monoplane.137 


PART 4 
BIPLANES 


1. Building the Biplane Cub 

2. The N-Strut Biplane . 


. 151 
. 157 








PART I 


GLIDERS 








1 


THE MIDGET BALSA SAILPLANE 

Can a tiny, all'balsa glider fly well? Build this little 
sailpleine, and see for yourself. Trim lines it has, with its 
shapely fuselage and slender wing. It has a very high aspect 
ratio; that is to say, while the wing spread is 20", the chord 
of the wing is only and this, together with the fact 
that the supporting surface is cambered, makes a very 
efficient flier. 

This little plane glides nicely indoors, but of course 
does better outside. The writer’s model, on a cool day 
with winds none too favorable, stayed up more than a 
minute when launched into the breeze from a hill side. 
On a hot, dry day with a proper wind, it might sail for 
two minutes. 

But few materials are needed. Get a piece of tV" balsa 
veneer % by 12", for fuselage, stabilizer, and rudder; and 
for the wing, a piece of *4 by % by 20" balsa. A small 
ring paper clip, bits of nails, and ambroid cement complete 
the list. 

Make a paper pattern of the fuselage. Notice that the 
under edge is gently curved most of the distance from the 


11 


12 ■ JUNIOR PLANES 

tail end, but rounds upward sharply at the nose. The 
upper edge is an almost flat curve from the nose to the 
cockpit, which is wide, situated IV 2 " from the nose. 

A straight slope from the 
cockpit to the tail com' 
pletes the body of the 
machine. 

To make the wing, carve 
out the underside with a 
gouge, and smooth with sandpaper on a round^edged block. 
Most of the curve, or camber, is near the front edge. When 
the under side is carved, shape the upper side, reducing 
the wing to a thickness of less than Wrap the sand' 
paper around a block of wood when smoothing the wing, 
as this will help to keep it straight. Cut the tips round, 
and then round the edges. 

You may find, after going to all this trouble to give 
camber, that the wing has flattened out. If this happens, 
wet it on both sides with water, and lightly wind it with 
string, having the loops no more than V/' apart for full 
length. Draw the string tightly enough to bring back the 
curvature, and lay the piece aside to dry. Be sure, however, 
that it does not lie in a twist. 

After drying, cut in from the edges toward the center 
at the middle, until the tips can be bent up 2" for the 
dihedral angle. Apply cement above and below the break. 





THE MIDGET BALSA SAILPLANE 13 

then block into position, and let the wing dry thoroughly. 

The stabilizer is V 2 by 5". Carefully shave and sand 
it until it is no thicker than a thin visiting card. When 
using the sandpaper, lay the balsa on a flat block of wood, 
and there will be no trouble in thinning it evenly. T rim 



Cut a Vi" sht in the tail end of the fuselage. It should 
follow a line drawn along the center of the body, and must 
be widened until the stabilizer can be slipped into it. Put 
ambroid on the edges, and above cind below the stabilizer 
across the center, before inserting the latter in the slit. 
Hold it at right angles to the fuselage until the glue has 
stiffened enough to keep it in place. 























14 


JUNIOR PLANES 


The tail, or rudder, is Vi by 1", and the same thickness 
as is the stabilizer. Ambroid it to the upper edge of the 
body, above the stabilizer. 

Cement the wing to the body, having the leading edge 
214" back from the nose, and 14" higher than the trailing 
edge, measuring from the center line. Fit A" square 
blocks against the body and beneath the wing, so as to 
strengthen the joint. After the glue has dried, streamline 
these blocks. 

The glider is now ready for flying. Slip a small paper 
clip over the nose, and two 14" lengths of nails about ^ 2 " 
in diameter through the wood under the upper edge of the 
clip, where they are cemented. 

Launch the plane by tossing it lightly forward and a 
little downward. If it repeatedly nosedives, take off some 
of the weight, but if it stalls when thrown fairly hard, add 
a little more. If it turns to the side when fair with the 
wind, give a little twist to the tail. It may be, too, that 
the wing is a little twisted, causing one side to drag. If so, 
breathe on that part, to moisten it, and twist it back. 

Long flights must be made from a hill side, where the 
wind, not too strong, blows toward it. If the breeze is 
right, the little plane may rise quite high before beginning 
its final downward glide. 

For short glides indoors, remove the bits of nails and 
try the ship on slow glides. Add a pin if necessary. When 


THE MIDGET BALSA SAILPLANE 


15 


pointed almost straight down and released from a height 
of seven feet, it should level off and skim away before 
touching the floor. 

The little plane may be decorated by staining it with 
water colors or rubbing it with wax crayons; but be sure 
that it is not twisted when drying, or it will remain that 
way. 


2 


A THREE^FOOT BALSA GLIDER 

It is said that a condor, high in the air, can come into 
sight as a tiny speck in the east, soar on outstretched wings 
overhead, and disappear in the west, without so much as 
flapping once to supply motive power for his flight. 

Flying men nowadays are spending much time studying 
soaring, and motorless gliders have stayed aloft many hours. 
Such flights are possible because in many places the wind 
blows upward with a good deal of force. For instance, a 
breeze moving toward a hill is turned upward. When a 
glider is launched by towing it down the hill at the end of 
a shock cord, it rises like a kite, gaining considerable eleva- 
tion after being released, for the pilot guides it skillfully in 
the rising air. Actually, he is not flying upward according 
to the air, but is gliding downward, at a slower rate, how- 
ever, than the upward speed of the current. By circling, a 
great height may be reached, when he can steer toward 
some distant hill where another rising current will carry 
him aloft once more. 

He may be fortunate enough to fly over a hot, bare 
stretch of fields and rocks, where the heated air rises almost 


16 


A THREE'FOOT BALSA GLIDER 


17 


as strongly as at a hill. Then his chances for a long flight 
are very good indeed. 

Some wonderful flights have been made by large, welh 
built model gliders. Durations of half an hour are not 
unknown. This chapter describes a simple balsa glider 
that will soar splendidly over a hillside in a fair bree2;e, 



or will make long, graceful glides above the level after a 
light toss from the hand. 

For this model a piece of Vs by 3 by 36" balsa, and 
one Vs by 2 by 24" are needed; also two pieces V 2 by V 2 by 
3", a piece of lead or solder that can be pounded into a 
flat strip tV by t® 6 by 2", and some ambroid cement. 

Use the 3" balsa for the wing. Gauge it for width 
along the center, cut it 35 V 2 " long, and square a line across 
the upper side 13" from each end. Measure back 2" from 
the leading edge at the ends, connect these points with the 




18 


JUNIOR PLANES 


width at the cross lines, with straight pencil lines, and 
trim the taper with a ra 2 ;or blade. Cut the corners of the 
ends, finishing by rounding them smoothly. 

Sand the wing on both sides, then taper the thickness 
of the edges by sanding them down from the upper sides, 
making the leading edge fairly blunt, with a short taper, 
and a long taper behind. 

Now place a wooden block under one cross mark and 
another 3 ^/ 2 " from the far wing tip. Press down on the 
other mark with the edge of a ruler, until the balsa touches 
the bench. Still holding the ruler there, push the blocks 
gradually toward the ruler until the balsa cracks beneath, 
but be careful not to break the tip entirely off. Crack the 
other tip in the same way. Then fill the ragged under' 
cracks with ambroid, block the wing with the tips 4^2^ 
above the center, and let the wing dry. 

Make two quarter^streamlined blocks long, using 
the Vi square blocks. These resemble parts of a cigar 
quartered lengthwise, but with the thickest parts forward 
of the center. 

When the wing is dry, square a line across the center, 
on the underside, and glue the blocks each side, with Vs" 
between. 

The fuselage, of neatly streamlined shape, is 13^^" long 
and VA'" at the widest point. 

The tail is Vs by 2". Notch one end to fit around the 


SLrLead strip iVx|x2- 



RZAK. ELEVATION A THREE " FOOT 

BALSA GLIDER 














































20 


JUNIOR PLANES 


trailing end of the fuselage, as the drawing shows, and 
glue it there. Then shape it up with the razor blade. 

The stabilizer remains. Use a piece of balsa Vs by 2 by 
8 ". Trim it with the tips sloping back from the center Y&'- 
Round the comers to a radius of Vs'V and taper the thicU 
ness. Across the center cut a slit to fit over the top of the 
tail, where it is glued with the leading edge above the 
fuselage and Vs"" lower than the trailing edge. 

Hammer and trim the lead to shape, bend it into a 
“U,” cind force it on the nose of the fuselage, where it is 
glued. 

Put the wing astride the body, 3" back of the nose. The 
blocks should clasp tightly enough to hold it for trial 
flights. 

Glide the plane by tossing it forward and a little down. 
Move the wing forward or backward, until a good glide is 
obtciined, and glue it in position. 

For soaring, climb a hill on the windward side, cast the 
ship against the wind, and watch it go. 


3 


A CONVERTIBLE GLIDER 

Gliders have a great point in their favor—they need no 
rubber for motors, and so are very inexpensive to fly. Boys 
who are fortunate enough to live on or near hills can have 
as much sport with gliders as with powered models. 

The Convertible Glider is an eflicient little sail plane 
that is easy to build, and that can be made into a powered 
machine simply by adding a bearing, a propeller, and a few 
rubber bands. 

These materials are needed: For spars and ribs, four 
pieces of tV by Vs by 20''; for the stick, one piece Vs by 
V4 by 10"; for the saddle, 1 piece Vs by V2 by 2"; for nose 
weight, 1" of Vs" wire solder; also rice paper 4 by 20", 
ambroid cement, mucilage, wing dope, and a rubber band of 
iV" square stock. 

Divide two of the 20" spars into spaces for the placing 
of ribs, measuring 3%" from the ends for the first inner, 
and the same distance farther on for the next. Cut seven 
ribs 2" long, and glue these on top of the spars. 

Bend the spars at the middle to make a dihedral 2" deep. 
Roll a pencil along the forward ends on the undersides of 
21 


22 


JUNIOR PLANES 


the ribs, giving a shallow camber to the wing, and cover 
the upper side with paper, applying mucilage to the leading 
and trailing edges, and all ribs. Cover only half the wing 
at a time. 

Sand the stabili2;er spars 
and ribs to iV' thickness. 
Cut two spars 6" long, three 
ribs IV 4 ' long, and assemble 
them as the wing was put 
together. The ribs, however, 
are left flat. 

Build the tail of by Vs" stock. For the base use a 
piece 2%" long; for the trailing spar, a 2" length, and for 
the other two pieces such lengths as will shape up the tail 
illustrated. The projecting front end of the tail base is ce- 
mented under the stabili 2 ,er, and the whole assembly is ready 
for mounting. 

The body stick is merely the heavy balsa sanded smooth, 
with the tail glued beneath. 

To carry the wing, a streamlined saddle is shaped, V" 
form above to fit the dihedral, and rounded below. Cut a 
slot lengthwise to fit over the stick. 

Bend the solder into a “U’’ to fit the front end tightly. 
Cement it there. Also tap the front end lightly with a 
hammer to mushroom it a bit as an extra help to keep the 
weight from slipping off. 






A CONVERTIBLE GLIDER 


23 


Loop the rubber band over the stick and wing, and 
adjust the saddle so that the leading wing spar rests on its 
front end, while the trailing spar slips past the saddle end 
and bears on the body stick. 

The ship is now ready for a trial. It will ride about right 
with the wing IVi' from the front end of the stick, but a 



little shifting backward or forward will probably be needed 
to get a good glide. 

Launch it with a light forward and slightly downward 
toss, against the wind. There is much sport in gliding it in 
the street or any open space, but to get a long flight it is 
necessary to launch it from a hillside when a soft breeze 
is blowing up the slope. The thrill of seeing it jockeying 






























24 


JUNIOR PLANES 


in the wind will repay any work expended in making it. 

If you wish to add a propeller, carve it from a balsa 
block Vs by 1 by 7", using a sV' music wire shaft and tail 
hook, and if a winder is to be used, an S-hook of the same 
wire. 

For a bearing use a re by Vs by IV/' aluminum strip, 
bent up suitably and cemented to the nose of the stick in 
place of the solder weight. 


4 


BUILDING A SIX'FOOT SAILPLANE 

Build the sailplane described in this chapter, and you 
will have a ship that will stay aloft as long as anyone could 
wish. The original was designed by Martin Moad, a sixteen' 
year-old Los Angeles school boy, who has some 200 plane 
models to his credit. It has made flights of nine minutes— 
purposely limited to keep the model for measurement. 

Use soft balsa for all wooden parts. Cut the wing spars, 
smooth them with sandpaper, and round the comers. Lay 
them in position on a bench for a center width of wing of 
with SVs" at the ends. Hold them with pins at the 
edges, being careful to make a uniform curve in the trailing 
edge. Lay out for ribs 5" apart on centers. 

Take the rib lengths from the frame, and raise their 
cambers by rolling the undersides with a pencil. Scarf the 
ends for cementing to the tops of the spars. 

Shape the bamboo wing tips over a candle flame, hold' 
ing the glossy sides out, and bending gradually. Glue them 
to the outer edges of the spar ends, flush with the top, and 
bind with thread, which is drawn across the wing to pre' 
vent spreading. 


25 


26 


JUNIOR PLANES 


For the dihedral, break the undersides of the spars at the 
middle, so as to raise the wing tips SVz", where they are 
blocked until the cemented breaks can dry. 

Cover the upper side of the wing with rice paper. 
Mucilage is good for this work, as it dries slowly, giving 
time for adjustments. It is necessary to paste the tissue to 
all the ribs. 



For the fuselage cut the longerons, and shape the dia¬ 
mond bulkhead to pattern. Make the notches to fit the 
longerons, trim the sides, and cut out the center. Break 
the longerons 6 %"" from one end, as the wing spars were 
broken, and cement them into the bulkhead notches. Ce¬ 
ment the ends of the top and bottom longerons together, 
and miter the other strips to fit against them. 










































































































28 


JUNIOR PLANES 


Put in the cross posts, butting them between the longe' 
rons to hold them straight. Pieces are also mitered between 
the longerons 3" from the nose, and two such struts, 2" fon 
ward of the bulkhead along the upper spar, incline backward 
at the lower ends. Cut away the section of the upper longe¬ 
ron between these braces and the bulkhead, and glue in the 
music-wire sides joining the bulkhead, thus trimming 
the cockpit. 

To prevent the paper cover from sagging inward from 
air pressure, glue a horizontal semicircle of Vs” balsa to 
the bulkhead, 1" below the side longerons. 

A by A" bamboo strip curved upward at the trail¬ 
ing end and glued to the underside of the fuselage nose 
acts as a landing skid. The tail skid is a large pin or other 
short wire stuck into the lower longeron 4" from the end. 
Make the wing cleat to be glued to the upper longeron to 
carry the wing. 

The towing hook is tied and cemented in a groove in 
the underside of the bamboo, directly beneath the nose. 

Cement and tie in the nose two pieces of solder or 
lead, one Vs by Vs by IVs”, the other, above it, IVs” long. 
Both are pushed forward as far as possible. 

Cover the fuselage with rice paper. 

The elevator stabilizer is next. Draw a pattern of one- 
half on a board, remembering that the inner rib fits against 
the fuselage, and so is at an angle. Notch the inner ends 


BUILDING A SIX'FOOT SAILPLANE 


29 



into a streamlined rib Vs" thick, and the other ends into 
a semicircular tip Vs" thick. Taper the center spar into the 
tip, round the leading and trailing edges, and build the other 
half of the elevator. Cover both surfaces with rice paper. 

Attach the elevator halves to the fuselage by means of 
two sV' wires thrust through the body and projecting Vz" 
into the leading and center spars, and cement. 

The rudder is much like a halhelevator. The lower rib. 








30 


JUNIOR PLANES 


however, is in two parts, the forward end inclining upward 
to fit the fuselage, and the rear half at 45 degrees with the 
center spar. Push a wire dowel into the end of the center 
spar end and the fuselage longeron, and nail the leading 
spar with a pin. Brace the rudder with a fine thread through 
the tip, connecting with the elevator tips. 

Cement the wing to its cleat, further securing it with 
pins having celluloid washers under the heads. Then 
make the two pairs of streamlined struts, cementing and 
pinning one end of each to the fuselage under the bulkhead 
and the other end to the wing, the front one under the 
third rib from the center, the trailing one 1" beyond that 
rib. 

Test the plane on the level, casting it a little downward. 
The weight in the nose may need increasing, or the angle 
of the stabili2;er may need changing. 

This plane has a remarkably flat gliding angle. It will 
make excellent flights if launched from the hand on a hill 
side, but for real endurance and altitude it should be towed 
with a shock cord. Use two strands of tV'' square rubber 
with a small metal ring tied at one end to go over the towing 
hook. With a boy to launch the plane, and one to tow it 
against the wind, it rises quickly. When enough elevation 
has been gained, the one towing should stop and twitch 
backward on the cord to release it from the hook. 






































































































































































































































































































































































































































































































































































































































































































































































PART II 


STICK MONOPLANES 
1 

THE ROUGH AND READY TRACTOR 

The Rough and Ready Tractor is a solid little plane, with 
wheels on the Itinding gear permitting it to take off from 
the ground. A staunch little flier it is. It whistles through 
the air in a steady climb, and if it perches in a tree or 
collides with a telephone pole, more likely than not it re' 
ceives no other damage than a bent propeller shaft. 

For this ship have the following materials: For motor 
stick, one piece of balsa by 14 by 13%"; for wing spars, 
ribs, etc., 614' of 14" square balsa; for the propeller, a piece 
of % by 1 by 6"; for landing gear, etc., sV" music wire 
about 2 ft.; for propeller shaft bearing, a fine 1 or 114" 
brad; rice paper 6 by 14"; for the wheels, stiff paper 1 by 
4"; also thread, ambroid cement, wing dope, and 4 ft. of 14" 
flat rubber. 

To make the wing, cut two spars llVi" long, and seven 
ribs 3" long. Mark the spars for the ribs, spacing them IVa 
apart, and cement them to the rib ends, the ribs lapping 
33 


^4 JUNIOR PLANES 

above. When the cement is hard, glue rice paper over the 
frame, drawing it tight. Smear a thin coat of glue or paste 
on the wood, including all the ribs. 

Partly break the spars at the center, coat the breaks with 
cement, and bend the wing 
so that the ends are 1" 
above the center, blocking 
the part in that position for 
drying. The right end 
should be twisted slightly 
upward toward the front, 
so that the rubber motor will not whirl the plane. 

Bend the two wing stirrups as shown, so that the ‘'"U” 
centers will clasp the motor stick firmly. Cement the ends 
to the upper sides of the spars, and bind them with a few 
turns of thread. 

The motor stick is sandpapered smooth, with the cor¬ 
ners a little rounded. Make the tail hook as shown in the 
drawing. Push the other end through the motor stick 2" 
from the rear end, sloping it backward, and bend the wire 
to form a skid. If the motor is to be wound by turning the 
propeller, slip over the hook a bit of rubber tubing; but if 
a winder is used, make an ''S’' hook to join the rubber with 
the tail hook, and put on the tubing. 

Heat the brad red hot to soften it. Cut off the head, 
bend the nail around a piece of the wire, and y% from the 






THE ROUGH AND READY TRACTOR 35 

eye bend the point back nearly at right angles. Flatten this 
part by hammering, cement it to the forward end of the 
motor stick, on top, and wrap it with thread. 

The stabili 2 ;er is made of two 5" spars and four PA" 
ribs. This is cemented across the under edge of the motor 
stick at the rear end, with the paper side down. 



tween two ribs, with sides flush. It is covered on one side 
with paper, and is cemented to the top of the motor stick, 
over the elevator. 

Paint all paper covering with wing dope. 

Lay out the propeller carefully. Draw diagonals on both 
faces, and circles at the centers. Saw along the diagonals. 







































36 


JUNIOR PLANES 


leaving a little wood each side of the marks to strengthen 
the hubs, and whittle the backs of the blades. Sand them 
smooth, a little hollowing, before carving the fronts. When 
well shaped, trim the comers of the tips round. 

Bend a V 4 ' hook on a piece of wire, leaving a straight 



shaft 2" long. Press the end through the propeller hub, 
bend over the end, and cement. 


Before adding the rubber tubing to the hook, slip on two 
glass beads for thrust bearings, and put the hook through 
the brad eye. 

The landing gear stmts are bent up as shown, so as to 
clasp the motor stick as do the wing stirmps. As they spring 
apart a little when carrying the weight of the plane, the 





THE ROUGH AND READY TRACTOR 


37 


wheel spindles are bent downward somewhat at the ends, 
so that, when standing on the ground, the wheels will be 
upright. The struts are pressed on the motor stick 3" from 
the front end. 

Make the brace. It clasps the stick IV 2 " in front of 
the struts, and the ends wrap around the struts about half' 
way down. 

To make the wheels, cut four 1" circles from stiff pa' 
per, and cut each radially to the center. Fold a little Ys" 
from the cut, spread glue on this flap, eind close the cut edge 
over to the fold, pressing the flap behind. This makes a 
cone. 

Cement two cones, at the edges, to form one wheel, and 
thread the strut ends through the centers. A little blob of 
cement each side of the wheel, on the wire, keeps it from 
slipping sidewise. 

Put the wing in place on the motor stick, the front edge 
about 5" from the front end. Loop a rubber over the motor 
stick before and behind the plane and under the wing, to 
prevent its working off. 

Put on four strands of Vs" flat rubber, short enough to 
hang rather straight without being stretched. Before launch' 
ing, wind the propeller backwards until two rows of knots 
are seen. If the ship settles on the tail, move the wing back 
a bit; and if it nosedives, move it forward. 


2 


THE TUMBLE BUG 

The Tumble Bug is a little tailless plane, and a pusher. 
A regular clown it is, for it just can’t behave. It darts away 
from the hand of the launcher, looping and zooming, cir¬ 
cling and zig'Zagging, as likely as not returning to give a 
peck at one’s head. If a thrilling flight is wanted, this plane 
is certainly the one to give it. 

To build the Tumble Bug, these materials are needed: 
One piece of balsa 3 % by A by 7"; for the wing, balsa 
% by 12"; for the propeller, balsa V 2 by % by 4%"; for the 
shaft, etc., 5 ?" music wire 8 " long; also two small washers, 
a glass bead, ambroid cement, wing dope, rice paper 3 by 
15", and 14" of Vs" flat rubber. For the bearing, have a 
piece of aluminum 3*2 by Vs by Vs". 

In laying out for making the wing, draw on a board 
two lines 2*4" apart, and a third P/s" from the second. 
Square a center line across them, and 5 V 2 " each side make 
two other lines. From the balsa split off two spars gV" 
wide. Cut two halves for the front spar, fitting them to¬ 
gether to sweep back from the center at the first line to the 
second at the ends. The rear spar sweeps back from a point 
38 


THE TUMBLE BUG 


39 


at the center 1 }/% behind the leading spar, to the back line 

at the ends. Cement the 
center ends, and ambroid 
a 1^6 by 3 ^ 2 " rib there. 
Also cement ribs between 
the ends. When nearly 
dry, bend the spars at the 
center until a dihedral an- 
gle ly/i deep is formed. 
Cement again, and let 
dry. Finally cover the upper surface with rice paper glued 
both to the spars and the ribs, but do not dope yet. 

Two rudders are to be made next. The detail in the 
drawing clearly shows their form. They are 2" high, iVs' 
wide at the top, and iVs" at the bottom. The frames are 
of T6 by Vs" balsa, with the top butted between the sides, 
and the sides butted against the lower rib. The lower ribs 
are cut long, so that they can be fitted between the rib spars. 
Cover them on one side with paper. 

Draw a pencil line IV 2 ' from each end, and parallel to 
it, on the wing. Carefully slit the paper along this line. Fit 
the rudders between the spars at these points, coat the sides 
and ends of the lower ribs with cement, and glue the tails 
in place. Be sure to get them parallel to each other, and 
upright in relation to the wing. Paste the wing covering 
neatly to the lower ribs. When dry, dope the paper. Twist 





40 


JUNIOR PLANES 


the right end slightly to prevent the motor rubber from 
turning the plane over sidewise. 

Now smooth the motor stick and round the lower end' 
corners. Bend a nose hook as shown, push one hook into 
the front end of the stick, where it is cemented, and drill 



the aluminum bearing with a hole just large enough for 
the music wire propeller shaft. If you have no #60 drill, 
flatten the end of a fine brad, file a point on it, cut off the 
head, and use it in place of a regular drill. Bend the bearing 
end up, and trim the rest to fit the top of the motor stick. 
Cement it there, giving it two or three coats to make sure 
it sticks. Sand the stick comers round. 
























THE TUMBLE BUG 


41 


Bend the wing stirrups next. Fit them to the motor 
stick, making the legs of the front one long, and those 
of the rear, Bend the ends at right angles for points to 
go into the spar edges of the wings. Be sure to get the 
short one in front, and cement well. 

The propeller is true pitch. Draw diagonals on the faces 
of the balsa blank, and draw hub lines Vs"" apart at the 
center to meet the diagonals. Carve the insides of the 
blades first, then the outsides, reducing the thickness to 
less than V"8"". Round the ends and edges, and sand smooth. 

Cut the shaft iVi’ long. Bend a rubber hook on one 
end, thrust the straight shank through the propeller hub, 
from the front, and bend the end into a hook to push into 
the hub. Cement the wire. 

Thread a small washer, a bead, and another washer over 
the shaft, before putting the hook through the bearing. 

Two strands of Vs"" flat rubber are needed for the motor. 
Tie the ends together to form a loop V"s"" longer than the 
distance between hooks, pull the knot hard, and trim the 
ends close. Put the knot at the front hook. 

Adjust the plane for a rather steep glide, pushing the 
wing back if the plane sits on its propeller, and forward if 
it goes into a nosedive. Wind the propeller backwards until 
oi>e row of knots appears in the rubber, and try a flight. 
After the rubber has been used a few times, wind it until 
a scattered row of third knots appears. 


42 


JUNIOR PLANES 


It may be necessary to twist the rudders to get a good 
flight, and this can be done by grasping the upper ribs with 
the fingers. If the joints are loosened, cement them with 
the proper twist. 

With a little care, the plane can be made to fly straight, 
but the flight is more thrilling if it darts around in circles 
and makes loops. The latter are caused by moving the wing 
slightly forward of the level flying position. 

If it is desired to use a winder for the plane, make an 
S-hook to hold the front end of the rubber and to loop into 
the front hook. The rubbers, of course, will need to be 
shortened a little. Talcum powder rubbed on the strands, 
or an even coat of glycerin, lubricate them and keep them 
from chafing when tightly wound. 


3 


A HYDROPLANE TRACTOR 

This brisk little hydroplane takes off from the water 
and hums through the air in a very business'like manner; 
but it can be flown from the hand, on land, just as well. 
After all next to building it, the pleasure of having an ain 
plane model consists in seeing it fly. 

For materials, have the following: For motor stick, one 
piece of soft balsa Vs by 1^5 by IT'; for wing and pontoon, 
■h" veneer Yi by 12"; for propeller, a piece V 4 by 1 by 6"; 
for tail assembly, hooks, etc., 15 Y' music wire, 4 ft. long; for 
bearing, aluminum by Ms by VY’; also rice paper, 6 by 12", 
ambroid cement, wing dope, light wrapping paper, shellac, 
fine thread, cind 42 inches of Vs" flat rubber. 

To make the wing, draw the outline on the work table 
or a flat board. Make a rectangle 3 by 13", dividing it in 
the center. Measure from the front edge V 2 " back on the 
ends for the leading spar, and place points 1%" farther back 
for the tr ailin g spar. Connect these lines with the center 
ends, and the main shape of the wing is determined. 

Cut the spars from YY' balsa as Vs" strips. Sand them to 
lY' thickness at the ends, tapering from the centers. Also 


43 


44 


JUNIOR PLANES 


taper the width to 3 ^ 2 " at the ends. Break the spars at the 

center, place them on the 
pattern, and cement the 
breaks. Trim the ends 
from the pattern ends. The 
three ribs are tV by Vs". 
Glue them on top of the 
frame. When dry, lift the 
frame and cement and tie the music-wire tips, finishing the 
wing with neat curves. 

This dry, crack the spars at the center and bend the 
wing into a dihedral 1V 2 "" deep. Cement, and block until dry. 

Now cover the upper side with rice paper and dope, 
and twist the left wing while drying, to oppose propeller 
torque. 

The stirrups are shown in the drawing. Bend the ends 
to fit the dihedral, and make the front stirrup Ys" shorter 
than the hind, so as to give the necessary angle of incidence 
to the wing. Cement these clips to the upper sides of the 
spars. 

The tail is a single piece of music wire bent as shown, 
with paper cemented on one side. Notice that the ends of 
the frame cross. The hori 2 iontal end is thrust into the motor 
stick and the vertical end is cemented to the end. 

The stabifeer also has a single-piece wire frame. Cover 
the under side with rice paper. 






A HYDROPLANE TRACTOR 


45 


For pontoon sides cut pieces of 3^2" veneer Vi by 4". 
Notch the upper comers 3%" square, to receive the ends of 
the cross pieces. Round the forward under edge. Notch 
the step 2^/2" from the fore end, tapering the hind part 
a little and ending with a curve. Sand to lY thickness. 



The cross pieces are -iY square and 2 %" long. Cover 
the pontoon with thin wrapping paper, and shellac it. 

In bending the stmts, be sure the upper clips are nar^ 
row enough to grip the motor stick firmly. The lower ends 
are bent at right angles, to stick into the pontoon sides, 
where they are cemented. The rear stmt attaches to the 
center of the back crosspiece. 

Sand the comers of the motor stick, and glue the stabih 
izer and tail to one end. Twist the stabili2ier down in front 






46 


JUNIOR PLANES 


until the leading edge is a little more than tV" lower than 
the rear. Bevel the under side of the front edge to meet the 
bearing, to reduce air resistance. 

For the bearing, drill a #60 hole in one end of the 
aluminum, bend Vs" of that end at a little less than 45 de' 
grees. Bend the base another 45 degrees, fV" from the first 
bend, and cement and tie to the top of the motor stick. 



Attach the wing to the stick about half-way back. The 
pontoon front struts attach about 3" from the bearing, and 
the hind strut far enough back so that, when the plane 
rests on the pontoon, the front end is 1" higher than the 
stabilizer. 


































A HYDROPLANE TRACTOR 


47 


Bend a tail hook, push the end through the stick, and 
bend under. Cement it. 

Carve the propeller from a Vi by 1 by 6" blank. Draw 
lines from comer to comer, and a couple of lines Vs" apart 
at the center, for the hub. Carve the blades flat, then hoh 
low the backs and round the fronts, to a thickness of to". 

The propeller shaft is cut 2Vi' long. Bend a hook on 
one end and push the other end through the hub, bending 
it into a hook which is pushed into the wood. Slip on 
three thin washers before putting the shaft through the 
bearing. 

Make an S^hook for use with a winder, and install a 
founstrand Vs" flat mbber motor, allowing Vs" slack. 

Now for flying. Adjust the wing for a good glide with¬ 
out power. Mark the position. Wind the prop backwards 
until the second row of knots begins to show, cast the plane 
light forward, and if it stalls, bend the bearing forward a 
little, so that the propeller pulls downward more. If the 
plane nosedives, bend the bearing more vertical. 

To take off from the water, wind and set the ship on 
the water, letting go of the stick and prop at the same time. 
If the propeller pulls down into the water, dry the wing, 
and move the pontoon forward a little. It will be neces¬ 
sary, of course, to readjust the wing position for a good 
glide, and perhaps, as well, the angle of the bearing. 




4 


THE FLYING FEATHER TRACTOR 

This little plane is truly a feather-weight, for with two 
strands of rubber for outdoor flying, it weighs less than 
1/5 ounce, and if it is powered with one strand, for indoor 
flights, it is still lighter. And how it flies! It reaches a good 
elevation, and holds a level after the motor is nearly un¬ 
wound. 

Materials needed are: For wing and stabilizer spars, 
two pieces of by 3^2 by 14" balsa; for ribs, one piece of 3 V 
by 1^6 by 14"; for tail, one piece of #2 by by 11"; for the 
motor stick, one piece 3^2 by ifv by 12 "; for the propeller, 
one piece V 2 by % by 5"; for shaft, skid, etc., music wire 
about 6?^' in diameter and 12" long; 1" of rubber tubing to 
fit wire hooks; rice paper, 6 by 14"; ambroid cement, wing 
dope, thread, and two ft. of Vs' flat rubber. 

Build the wing first. Draw the pattern on a flat board. 
Lay over it a piece of waxed paper, to prevent glue from 
sticking the frame to the board. Drive a brad inside the 
spar centers and outside near the ends, and bend the spars 
around them. Simply glue the rib ends on top, without any 
attempt to butt them between. When dry, trim off all ends 
with a razor blade. 


48 


THE FLYING FEATHER TRACTOR 


49 


Cut the paper a little 
larger than finished siTie. 
Smear glue thinly on the 
spars and ribs. Press the 
paper on, stretching it as 
smoothly as possible, and 
trim to the frame when 
dry. A coat of dope completes it. While drying, it should 
be propped so that the right end is twisted downward a 
little, to overcome propeller torque. 

Smooth the motor stick with fine sandpaper. Make a 
propeller bearing of wire, by cutting a piece 2" long and 
bending it around a coarse needle, in the middle, until the 
two legs lie side by side. Squeeze the wire together beneath 
the needle with pliers, bend the legs back nearly at right 
angles with the eye, % below, and then bend the ends 
down again. Pull out the needle, straddle the ends over the 
motor stick, bind the middle part to the top with three 
or four wraps of thread, and cement. 

The tail hook and skid are one piece of wire 2" long. 
Push the wire through the motor stick, from top to bottom, 
inclining forward, about Va from the rear end, slip ^ 2 " of 
rubber tubing over it, and bend the end back so that it can 
be thrust squarely through the stick. Bend the lower end 
in a curve for a skid. 

Cut a notch in the upper edge of the stick Wa from 





50 


JUNIOR PLANES 


the rear end, and glue into it the stabilizer spar. Cut the 
ends off 2^^" from the center. Stick a pin in the motor 
stick 2" from the front of the spar, glue the end of a thread 
to the rear end of the stick, and stretch it around the spar 



stick. Square the spar with the stick before gluing the 
thread. 

When all is dry, pull out the pin and glue a piece of 
rice paper on the top. Trim the edges in the same way as 
with the wing. The paper is slit to slip over the motor hook. 

The tail is simply a right-angle triangle 3" wide and 3" 
high, covered on one side with paper. The front point is 
glued to the stabilizer and hook, and strengthened with a 
few wraps of thread. 








































THE FLYING FEATHER TRACTOR 


51 


Now bend two wire stirrups for the wing, as shown in 
the drawing. Gently crack the wing spars over the center 
rib, cement them, and prop the wing with the tips raised 1" 
for the dihedral angle. When dry, cement the stirrups in 
place, and slip them over the motor stick, with the wing a 



little more than half-way back between the front end and 
the stabiliser. 

The propeller is carved from a Vz by % by 5" balsa 
block. Draw diagonal lines on each face, saw nearly to the 
center, leaving 14" for the hub, and whittle the inside faces 
of the blades. Sand them smooth, and a little concave. 
Then carve the front faces. Thin the blades until light can 
be seen through them. The comers should be rounded. 










52 


JUNIOR PLANES 


Using ly/i of wire for the propeller shaft, bend a small 
hook on one end, slip rubber tubing over it, and press the 
other end through the propeller hub. Bend the tip at right 
angles, coat it with cement, and put it back against the prop. 
Slip two glass beads over the shaft before putting the hook 
through the bearing. 

The rubber is looped around the prop hook and tied 
together after being passed through the skid hook. It 
should be just long enough to hang straight between the 
hooks without stretching. 

For the trial flights, wind the propeller backwards until 
a row of knots appears in the rubber. Launch the ship 
pointing slightly upward. Move the wing forward or back-' 
ward until the proper balance is obtained, and then wind 
until three rows of knots have come. 

If a winder is to be used, do not attach the motor to 
the tail hook directly, but use an ''S’’ hook between, so that 
it can be easily removed. 

If the rubbers spring the motor stick too much, make a 
wire loop or "can” to put about halLway back, threading 
the rubber through it. 


5 


THE MAYFLY INDOOR TRACTOR 

The Mayfly Tractor, for all the world like some dainty 
white'winged insect, flutters lightly through the air, and 
though so small, stays up a surprisingly long time. It flies 
well indoors, and if there is no wind or only a soft breeze, 
out of doors cLS well. 

For the wings, a piece of balsa wide and 16" 
long is needed; for the motor stick, a piece by ^ by 9"; 
for the propeller, balsa Vi by Ys by 7"; for the bearing, hard 
aluminum at by Vs by Ys"; for shaft, clips, etc., sh" music 
wire 12" long; also rice paper 3 by 20", ambroid cement, 
thread, a couple of small washers, a bead, and 9" of Vs" 
flat rubber. 

Split from the it" balsa two wing spars tV' square. Lay 
them on a board, holding them with pins at the edges so 
that they measure IYa" from outside to outside. Cut them 
to a length of 14". Also cut from the veneer a 2" length of 
balsa to be used in making wheels. Then cut ribs, making 
them -h, by tV by 2y8". Roll the under sides with a pencil 
to give them camber, remembering that most of the curve 
is near the front end. When they bend about YY', miter 


53 


54 


JUNIOR PLANES 


the ends and cement them to the upper sides of the wing 

spars, where they are ah 
lowed to dry before more 
work is done on the wing. 

While the wing dries, 
make the stabilizer in the 
same way, using iV by 
16 by 4" spars, and ribs 
cut 3 V by tV by ItV. The ribs are rolled full length with 
the pencil, giving them a curve throughout, approximately 
the arc of a circle. 

Break the wing spars at the center, so that the tips can 
be raised 2", forming the dihedral angle. Cement the breaks 
and dry them, then cover the upper side with rice paper, 
half the wing at a time, spreading thin ambroid or mucilage 
on the end and center ribs, and the outer edges of the spars. 
Draw the paper as smoothly as possible. 

Cover the stabilizer with one piece, drawing the paper 
over the convex lower side. Trim the paper to the frame 
when the glue is dry. 

The tail frame has a base rib e? by %4 by 1%". The 
side and top pieces are e? by -re", making the tail IVs' wide 
at the top, P/s" at the bottom, iVs" high in front, and 1^4" 
high on the trailing edge. 

Smooth the motor stick and miter the front end, as 
shown in the bearing detail. Trim the lower edge of the 






THE MAYFLY INDOOR TRACTOR 55 

rear end to a slight taper, so that when the projecting end 
of the tail base rib is cemented to it, the rib will point a 
little downward in front. 

Bend a short S'hook of music wire, and press one 
hook into the rear end of the motor stick. The other hook 
rests on top of the stick to carry the end of the rubber. 



under side, hollow side up. 

Drill the piece of aluminum to fit the wire. Vs" from 
one end. Bend this end nearly at right angles to the rest and 
ambroid to the top of the free end of the stick. Bind it 
with a few turns of thread. 

For the landing struts, cut a piece of music wire 9" 










































56 


JUNIOR PLANES 


long, bend it into a clip at the center to fit around the motor 
stick, and bend the ends out so as to serve for wheel spin¬ 
dles. Cement the wire about 1" from the nose of the motor 
stick. 

The wheels are of tV balsa, and are in diameter. 



Mount them on the ends of the landing gear struts and 
cement them fast. They do not need to turn. 

In laying out the propeller for carving, draw diagonal 
lines from points on the edges of the faces from the 
ends. Also draw lines parallel to the edges tV" each side 
of the center, for the hub. Trim the edges of the blank 
to this outline, and then carve the insides of the blades. 
They should be about hollow. When smoothly sand- 















THE MAYFLY INDOOR TRACTOR 57 

papered, carve the fronts of the blades. Work carefully in 
this, and finish them less than iV' thick at the middle, or 
rather, forward of the middle, toward the leading edge. 
The thickness should decrease toward the edges. Trim the 
ends round, and cut in toward the hub until the thickness 
there, from front to back, is 

The prop shaft is cut 214" long. Bend a hook on one 
end, push the other through the propeller, and bend a hook 
on that end to press into the hub, which will make it fast 
when cemented. Thread over it a thin washer, a bead, and 
another washer, before putting the shaft in its bearing. 

The motor is a single strand of Vs" flat rubber, with 
holes in the ends pierced with a pin, to put the hooks 
through. 

To attach the wing to the motor stick, bend two wire 
stirrups, one with the legs V 2 " long, the other with legs %" 
long. Cut the wire long enough to allow of Vs" being bent 
back at right angles to each leg. Cement to the undersides 
of the wing spars, the short stirrup in front, the long one 
behind. 

Put the wing 3Vi" behind the propeller, and try a short 
flight of the plane. Move the wing back a little if the tail 
rides low, or move it forward if the ship dives. 

The Mayfly takes off from a smooth floor after taxiing 
two or three feet, and gains elevation quickly. 


6 


AN ENDURANCE STICK MODEL 

Simple as it is, this stick model is a wonderful flier, both 
for altitude and endurance. It was built by Martin Moad, 
a Los Angeles school boy, and like all the planes he builds 
nowadays, is a splendid performer. 

Have ready the following materials: For wings, tail, 
and stabili 2 ;er, three pieces of #2 by V 4 by 30" balsa, and one 
piece 3 % by #2 by 30"; for motor stick, one piece by A 
by 21"; for bearing, aluminum ei by by iVs"; also two 
pins, 15" of 6?'' music wire, small, thin washers, or old 
kodak film to make them of; thread, rice paper 10 by 30"; 
ambroid cement, wing dope, and 12 ft. of Vs' flat rubber. 

For wing spars sand smooth and round the comers of 
two pieces of 3^2 by Va" balsa. Mark the centers and lay off 
for ribs centered 3%" apart. 

Make the ribs ^2 by i%". Cut them a little more than 
5" long. Lay them on a pad of newspapers and roll the for^ 
ward ends one-third of the way back with a lead pencil. 
This gives the camber, the amount of curve being regu- 
lated by the pressure on the pencil. Bevel the ends, and 
cement them to the spars. Trim the upper comers to meet 


58 


AN ENDURANCE STICK MODEL 


59 


the spars, and round the wing comers. When dry, break 
the spars in the center and cement together with a dihedral 
angle 4" deep. 

Cover the upper surface with rice paper. Glue the 
paper to the leading edge, apply glue thinly to the upper 



surfaces of the center and end ribs, and glue to the trailing 
edge. When the whole wing is covered, block it with 
enough twist to raise the leading edge of the left end 
more than the other end of the wing, and dope. 

Notice that the iii" music wire stirrups are made with 






































60 


JUNIOR PLANES 


the points bent so as to thrust into the edges of the wing 
spars. The fore clip, being shorter than the hind, lifts the 
leading edge about which is a good climbing and glid¬ 
ing angle. 

The stabili2;er has two spars and three ribs, all made of 
3"2 by sV' balsa. The ribs, however, instead of lapping over 
the spars, as in the wing, butt between. They are rolled 
full length with a pencil, so that they are arcs of circles 
bulging Vs\ Cover the under side with rice paper. 

Sand the comers of the motor stick and round the under 
edge of the fore end, to reduce air resistance.. 

Shape the aluminum bearing. If you have no drill of a 
size to fit the wire, hammer a flat point on a brad and file 
it to a diamond shape, which will cut the hole. File off 
any burr, and trim the end round. Nip the comers from 
the other end. Bend as shown in the detail drawing. The 
bearing itself must not be exactly vertical, however. It 
slopes a little forward, thus making the propeller pull down¬ 
ward a trifle. 

Cement the bearing to the top of the motor stick, bind 
it with fine thread, and cement the thread all over. 

The tail is built next. For the base, cut a piece of 35 by 
ss" balsa 3%" long. Put a pencil mark on it 3" from the 
forward end, and taper the under side of the motor stick 
at the trailing end so that when the tail is glued to the 
taper, the lower edge at the pencil mark will be even with 


AN ENDURANCE STICK MODEL 61 

the lower edge of the motor stick. Cement it centering 
on the taper. 

The leading spar of the tail is 51/2" long, and the trailing 
spar, 5 y 8 ". The latter is butted on the end of the base, and 



the leading spar butts on top of the base and against the 
stick end. A straight rib between the upper ends completes 
the frame. Push a pin through the leading spar into the 
end of the motor stick, inclining it downward so the point 
will enter the base stick. Round the comers of the frame. 































62 


JUNIOR PLANES 



Cover one side with rice paper, dope it, and trim the edges 
when dry. 

Cement the stabili 2 ier, hollow side up, beneath the tail 
base stick, being certain that it is square with the stick and 
the tail. If it seems weak, brace it with a thread from the 


rear comers to the upper trailing comers of the tail. 

Carve the propeller from a balsa blank % by IVs by 12". 
The diagonals do not run from corner to corner, as with 
a tme-pitch propeller, but are drawn between points 3 in. 
from the ends. Round all corners when the carving is done, 
and sand the blades to le" thickness. 

Bend the hook in the propeller shaft, thrust the straight 






AN ENDURANCE STICK MODEL 


63 


end through the propeller hub, bend a hook and push it 
into the hub. Use three light brass washers or washers cut 
from celluloid. 

Make the ''S” winding hook, loop an eight-strand rub¬ 
ber motor with Vs" slack between the hooks, and try the 
ship for gliding. To overcome stalling, move the wing 
back, and for nose dives, move it forward. When a smooth, 
flat glide is obtained, wind the propeller until half the first 
knots show, and try it. Adjust the bearing angle until it 
flies under power with good altitude gains with the wing 
at a perfect gliding angle, and you are ready to use the 
winder. 

The plane, for ordinary flying, should be adjusted for 
circling, by warping the tail a little to one side or the other, 
since it will fly so far that it may not be recovered if allowed 
to go straight. Flown on a hillside, against a rising breeze, 
as a glider is flown, it might go out of sight. 


7 


A BRACED^WING MONOPLANE 

This little plane, like Lindbergh’s ship, The Spirit of St, 
Louis which he flew to France, is braced with a pair of 
struts attached to each side of the wing. Having no fu- 
selage, a vertical strut is brought down from the center rib 
to carry the lower ends of the struts. 

For this model these materials are needed: Motor stick, 
one piece of balsa -32 by -32 by 24"; for wings, two pieces 
^2 by #2 by 24", and two pieces by Vs by 18"; one piece 
16 by Vi by 24"; for the propeller, one piece Vs by by 
10"; for prop shaft, ''Y,” and S-hook, 7" of ^\" music wire; 
for wing tips, skids, stirrups, etc., 16" of eh"' music wire; 
for prop bearing, one piece of aluminum ih by uh by Vs''; 
three small washers; also fine thread, pins, rice paper 9 by 
30", ambroid cement, wing dope, and mucilage. 

Draw the wing on a board. Round the corners of the 
-32 by 3 V' balsa strips with sandpaper. Cut one 24" long, 
and lay it on the drawing, holding it with pins. The trail¬ 
ing spar must be broken at the center and cemented again, 
so as to fit the angle. It is cut off at the ends even with the 
leading spar. 


64 


A BRACED'WING monoplane 


65 



Make the center rib from a piece of tV by balsa. 
Notice that the curve is sharpest toward the leading end, 
with the highest point /g" from the lower edge. Hollow 
the lower edge each way from the widest point, to lighten 
it, and notch it to fit the spars. Do not cement it in place, 
however, until the other ribs are in position. 

The other ribs are cut about longer than the distance 
they span, using tV by Vs'' balsa. Round the corners, then 



66 


JUNIOR PLANES 


roll the undersides with a lead pencil, giving them camber. 
Lighten the pressure one third the way back from the 
leading ends, and with a ra 2 ;or blade trim the ends flat to 
fit the spars, where they are cemented. 

When the glue is dry, gently lift the frame a little and 
cement in the center rib. 

Cut 61 / 2 " of ih'" music wire for each tip. Bind the spar 
tips with thread, coat the wire ends with cement, and push 
them into the spar tips until the curved wire projects 2 ", 
giving a total wing span of 26". 

Break the spars partly through at the centers. Tliis is 
for the dihedral angle. Cement the breaks, and let them 
dry. 

Glue a Vs by Vs by 3^^" strut at right angles to the cen- 
ter rib, notching the upper end to fit at the side of the rib. 
Trim the comers round. 

Cut the four stmts by V 4 by 8 ^/ 2 ", tapering them as 
shown. Cement two of them to the end of the center rib 
stmt, with the other ends cemented under the leading spar. 
When dry, glue the ends of the other stmts over the first 
and cement their other ends to the trailing spar of the 
wing. Use care, though, to see that the wing is tme. Look- 
ing at it in front, with the spars of the wing to the left 
aligned, the leading spar of the wing to the right should 
rise a little higher than the trailing spar, giving that side 
lift to offset the propeller torque. 


A BRACED-WING MONOPLANE 67 

Cover the upper side of the wing with rice paper, one 
half the wing at a time, gluing it with mucilage to the outer 
edges of the spars, the center and the end ribs. Trim the 
paper with Vs" projecting outside the wire tips, and paste 



over the wire. Give the wing one coat of thin dope, run¬ 
ning a little along the under side against the unglued ribs. 

The stabilizer is made much the same, but with three 
ribs and no dihedral angle. Cover the ribbed side with rice 
paper, and dope. 

The tail is 2% by 4", a rectangle racked back at the 
top Va"- Cover it on one side with paper. 

The motor stick, with comers rounded, is curved at 
the fore end on the under side, and thinned at the tail end 
to Vs by A", leaving the upper side straight. 
















































68 


JUNIOR PLANES 


Drill the bearing aluminum Vs" from one end, bend 
the metal back at about 40 degrees Vs" below the hole, and 
bend again VV farther on, another 45 degrees. Cement this 
part at the front of the stick, and above it cement a small 
brace'block of balsa. Bind with thread, and cement again. 





A BRACED-WING MONOPLANE 

The “Y” wire is a fork to hold the hook end of the 
propeller shaft higher than the bearing, so that the pro^ 
peller will pull downward a little, keeping the plane from 
stalling. The lower end is thrust into the motor stick, with 
the offset cemented and bound to the stick. 

Cement the tail to the top of the stick, as shown in the 
drawing. The stabiliser is cemented hollow side up, to the 
under side of the stick. Push a pin through the spars into 














A BRACED'WING MONOPLANE 69 

the Stick and the tail, and a long pin diagonally through the 
stick, projecting above for a hook. 

Carve the propeller with blades A" thick. Bend the 
shaft, cement it in the hub, and install the propeller with 
its bearing. Hook four, six, or eight strands of Vs" flat rub' 
ber to the shaft and S'hook. 

Bend the stirrups, push the ends into the wing spars, 
and cement. Put the wing about halfway between the 
bearing tind stabilizer, push a wire skid into the tail and 
the tips of the wing struts, and glide the plane until the 
position of the wing has been found. Rim a guy'thread 
from the front end to the wing struts, wrapping it once 
around the skid, and bringing it back to the tail. Draw it 
tightly enough to bend the stick a trifle upward in the 
center. 

To keep the stick from bending sidewise, make the wire 
circle, or “can,” pushing the ends into the stick above the 
wire. Pass the rubbers through it. 

If the plane stalls under full power, a higher “Y” wire 
is needed, so that the prop will pull downward more. If it 
flies in short dips, the “Y” is too high. 

The ship flies well with four strands of rubber, circling 
at a height of about thirty feet; but for elevation, and a 
long glide at the end, more strands are necessary. 


8 


A TWIN^PUSHER PLANE 

Many endurance records have been made by twin pusher 
planes. They are easy to put in fore-and-aft adjustment, 
and the “A’’-frame, carrying two good motors, is light and 
very strong. 

The little pusher model described here is too small to 
have a great deal of endurance, but it is inexpensive to 
build, and will give much sport. 

For materials, get these: Balsa, two pieces A by 
j6 by 18"; one piece Vs by 1 by 22"; two pieces Vs by % 
by 6"; bamboo, one piece by Vs by 18"; aluminum, ttV 
by T^6 by iVi'; music wire, 12" of # 2 " diameter; also four 
celluloid washers, two glass beads, ambroid cement, dope, 
thread, two shingle nails, rice paper 6 by 16", Vs'" flat rub¬ 
ber, 10 feet. 

Cut the 1 ^ 6 square sticks 16" long, sand smooth, and 
round the corners. Taper the front ends so that, when 
glued together, the other ends are held apart 5 V 2 ". The 
cross pieces are of Vs'' balsa, V2" wide for the front, and 
Vs" for the rear. Sand these pieces to 3 %" in thickness, 
sharpen the ends from the sides, and cut in the edges, as 
70 


A TWIN-PUSHER PLANE 


71 



shown in the drawing, to lighten them. Sand off the con 
ners, press slits in the edges of the side pieces, and glue the 
pointed ends of the cross pieces into the slits. Glue the 
forward ends of the tV' pieces, and bind them with thread. 

Cut a 2" length of music wire, bend it at the middle to 


fit the front end of the frame, and twist the ends back into 
hooks. Cement this double hook to the frame. 

Make two aluminum bearings IV4" long, bending Vi of 
each back almost at right angles. Drill a propeller shaft 
hole in the shorter part of each, and glue and bind them to 
the rear ends of the frame sides, projecting Va" to the rear 
and outward. 



72 


JUNIOR PLANES 


Lay out the propeller blanks with diagonals drawn from 
points 1" from the ends. Be sure to carve them opposite, 
that is, one for turning right-handed, the other, left. 

Cut the propeller shafts 3" long, bend a motor hook on 
one end of each, and push the other into the hub of a pro¬ 
peller. Bend a hook on the projecting end to push into the 
hub for making it fast to the propeller. Cement it there. 

The wing spars are 141^2^ long. Make them jV' wide, 
sanding them smooth and rounding the comers. Also 
smooth five rib pieces Vs by by 3 tV' long, and roll them 
with a pencil on the under side to give them camber, curv¬ 
ing them more toward the front ends than at the rear ends. 
Miter the ends and glue them to the upper sides of the 
spars, a rib at each end, one in the middle, one in the center 
of each side. Break the wing spars at the center, raise 
the ends 1", and glue the breaks. When dry, cover the 
upper side of each wing half with rice paper, gluing it to 
the ribs as well as to the spars. After trimming away the 
waste, any ragged threads can be quickly removed by mb- 
bing fine sandpaper along the edges. Clip the wing comers 
with a razor blade. 

The stabilizer spars are Vs by by 6%". The three 
ribs are cambered in the same manner as those of the wing. 
The rolling compresses the thickness of the ribs to tV', as 
detailed in the drawing. Give the stabilizer a dihedral of 

Tie the wing to the top of the frame, just forward of 





pedpelle.il 















































































74 


JUNIOR PCANES 


the propellers, and the stabili 2 ;er to the front end. Glue a 

block under the forward edge of the stabilizer, thus giv¬ 
ing it considerably more angle of incidence than has the 
wing. Because of this, a good lift is given to the nose of the 
plane, preventing nosedives, and yet, if it is blown upward 
to the stalling point for the ship, its high incidence angle 
will make it “burble’’ before the main wing does, so that it 
will fall and bring the plane level again. 

No rudder is needed for this model. 

Install the propellers, bend an “S”-hook for each motor, 
and make a four-strand loop of Vs"" flat rubber for each prop. 

Glide the plane to find the proper position of the wing, 
before using any power, and then wind the motors only 
a little for test power flights. If these are satisfactory, wind 
up fully, and see it go. 

While the pusher plane flies excellently without landing 
gear, it is evident that it is more likely to crack up upon 
descending to the ground if it has neither wheels nor skids. 
The drawings suggest a landing gear that is easy to add, 
although it is not very suitable for taking off from the 
ground. 

Cut two pieces of tg by Vs"" bamboo AVi long, point 
one end of each, and, coated with ambroid, thrust the 
points into the forward end of the frame. Incline them out¬ 
ward iVs"" at the bottom. Glue between the back edges 
and the undersides of the frame square bamboo braces. 


Right-handed propeller 
































76 


JUNIOR PLANES 


For spindles, bend shingle nails with the head sections 
hori2;ontal when the points are bound to the sides of the 
bamboo struts. 

Shape wheels from Vs" flat balsa, push them over the 
spindles to the heads, and bind the nails to the struts. 
Smooth the binding with glue. 

The rear landing gear consists of a prop or skid bound 
and glued to the rear of each frame side. Bend the tip of 
the skid backward, either by heating over a flame, or by 
breaking the bamboo and cementing it at the correct angle. 


PART III 

FUSELAGE MONOPLANES 


















1 

A PUSHWLL SCIENTIFIC MODEL MONOPLANE 


For dependability and ruggedness of design the Push- 
Pull model is really splendid, and its unusual form in itself 
makes it worth while building. The dimensions given here 
are for an outdoor model, but an indoor model of this style 
could be made by greatly lightening the parts. 

The motor frame consists of two longerons lashed at 
the ends, spread into fish-shape with four cross-struts, and 
covered on both sides with rice paper. 

The following materials are required: Balsa, one piece 
by 2 by 18"; for propellers, one piece by IVs by 12"; 
landing gear, bamboo l e by Vs by 24"; 3 ^ 2 " music wire 12" 
long; sheet aluminum 3^2 by V 4 by 2^^"; four small celluloid 
washers; two glass beads; rice paper 12 by 24"; 12 ft. of Vs' 
flat rubber; also ambroid cement, wing dope, and thread. 

Cut the wing struts and pin them on a board, ready 
for assembling. Cut seven ribs, curving them by rolling the 
under sides lightly with a pencil, with the deepest curves 
about one-third the width back from the leading edges. 
Trim the rib ends to fit on the spars before cementing them 
in place on the tops of the spars. Cut the spars on the 
under sides, at the centers, so that a dihedral angle IVi' 
deep can be bent. Cement the joints, and when dry cover 
78 


A PUSH-PULL SCIENTIFIC MODEL MONOPLANE 


79 



the Upper side of the wing frame with rice paper, half at a 
time, with a lapping joint at the center rib. 

The stabilizer is flat, with two end ribs and two inner 
ribs which form bases for the tails. A double rudder is 
necessary because of the rubber motor above the body 


frame. Cover the stabilizer on the upper side and cement it 
on the trailing end of the motor frame. The tails are alike, 
with slightly staggered frames covered on one side with 
tissue paper. Glue these upright on the stabilizer. 

The front landing gear is constructed of two pieces of 
bamboo pointed at the upper ends and thrust into the under 
edges of the longerons about 114" from the nose. Brace 






80 JUNIOR PLANES 

these struts with similar bamboo strips cemented obliquely 
between the longerons and the struts. Use brads for wheel 
spindles. Cut the heads off and bend the ends over so that 
when the shanks are bound and cemented to the ends of 
the struts the spindles will be hori 2 ;ontal. Slip small cellu^ 
loid wheels, or wheels cut from balsa, over the spindles, 
and hold there with cement on the tips of the spindles. 

The tail landing gear consists of two bamboo struts 
shorter than those in front, cemented to the longerons. The 
lower ends are bent backward V 4 ' by cracking them and 
applying glue to hold them. 

The bearings are strips of aluminum, one cemented and 
lashed to the nose on top, the other underneath the tail. 
A tail hook of wire must be tied and cemented on top of 
the tail end, and a similar one underneath the nose. 

Carve two propellers from Vi by IVs by 6" balsa, being 
sure that one is left-handed and the other right-handed, so 
that both motors can be wound at once with a double 
winder. A glass bead between two celluloid washers forms 
a thrust bearing for each prop shaft. The wing is attached 
above the motor frame by means of rubber bands. Each 
motor requires four strands of Vs" flat rubber. Make two 
''S” hooks, both used at the tail. Thus, the rubber hooks 
directly on the front prop shaft, with an ‘■'S’’-hook between 
it and the tail hook, while for the lower motor the '’'S''’-hook 
is between the rear prop shaft and the rubber. 



IbmdONOVSLTiaOlAlOUliraiO^TIM-H^nd 














































82 


JUNIOR PLANES 


Varnish the wing and tail assembly cover with thin 
dope. When dry, place the wing, looping Ys" rubber under 
the body, over both sides of the wing, and under the body 
again. 

Adjust the wing forward or backward to a good gliding 
position, and the plane is ready for a power flight. Attach 
the ‘■'S^'hooks to a double winder and stretch the motors 
to a little more than twice their length. Wind about half, 
and give a short test flight. If the plane fails to gain altitude, 
cement a Ya' balsa block under the leading edge of the wing 
to give an increased angle of incidence, and consequently 
more lift. It is useless to increase the angle more than this, 
however, as the lift is decreased and the drag is greatly in^ 
creased. A little lifting of the trailing edge of the stabili 2 ;er 
may also help. 

It is almost impossible to stall this plane, so no down- 
ward pull on the front propeller is necessary. 

Since this is such a foohproof plane, it will last some 
time without a crackup if reasonable care is given it. This 
being the case, it is a good idea to ''treat'’ the motors to re- 
duce wear and to help prevent rotting. If the strands are 
shaken up with talcum powder they will slide on one an- 
other when in use, thus reducing friction and heat. Some 
boys moisten them with glycerine. Graphite, too, is good, 
but it is so dirty to handle that it is not to be recommended. 

When the rubbers are not in use, take them off the 
plane and lay them away in a fruit jar in a cool, dark place. 



























































































2 


THE TEENY WEENY MONOPLANE 

The Teeny Weeny Monoplane is a dainty little plane that 
is good for all kinds of flying thrills, for it loops, banks, 
zooms, and otherwise cuts capers in the air. Of course with 
careful adjustment, it can be made to soar in a very sedate 
manner, and with a fair amount of duration. 

Materials needed are: Balsa, one piece by IV 2 by 20"; 
Vs by 1 by 18"; 3 V' music wire 18" long; rice paper 10 by 
14"; two celluloid landing wheels; two celluloid washers 
and a glass bead; ambroid cement, wing dope, thread, fine 
wire. The propeller blank is Va by 1 by 6", and four strands 
of Vs'" rubber, or about 4 ft. are needed for the motor and 
for attaching the wing. 

Cut the wing spars and seven ribs. As the width of the 
finished wing is 2 V 2 '', the ribs must be about 2^8". Sand 
smooth, and roll the ribs for camber. Miter the ends for 
gluing to the upper sides of the spars, and when assembling 
the wing remember that the most curved parts of the ribs 
go forward. The leading spar is shorter than the trailing. 

When the frame is dry, break the spars at the center 
and cement them with the tips raised Wi'. 


84 


THE TEENY WEENY MONOPLANE 


85 



Cover the upper side of the wing, one half at a time, 
giving an upward twist to the front of the left side to offset 
the tendency of the motor to turn the plane over in an op- 
posite direction to the motion of the propeller. Cement 
under the leading spar center a Vs by Vs by lYz" balsa block. 


The top and bottom of the fuselage are made in one 
piece each. Draw on paper a rectangle IV 2 by 10", dividing 
it into Vi" squares, and through these draw half the out- 
line as shown in the drawing. Fold down the center and 
cut out, thus making one side exactly the reverse of the 
other. Trace this pattern on the tVj ^ balsa, and cut out. 






86 


JUNIOR PLANES 


The shaped top and bottom are joined together with : 
Vs" square posts. Draw them together with twine wrapped ' 
around the assembled fuselage until the glue dries. The 
tail post, it will be noticed, is reenforced with a 2" length of 
music wire cemented and bound to the back edge, the part 
projecting below being bent back into a tail skid. 

Cover all over with rice paper, and then cut an opening 
in the nose, back to the front post, and a like opening in the 
rear (left side only) for inserting the motor. 

The stabilizer is flat, having ribs butted between the 
spars. Like the wing, the ends are not square. The shorter 
spar is in front. Glue this to the top of the fuselage, with 
a To" balsa block under the trailing edge. 

The tail fin is like a half-stabilizer. Cover it on one side 
and glue upright on the center rib of the stabilizer. 

In making the landing gear, cut a piece of music wire ; 
9%" long. Four inches from each end bend the legs down¬ 
ward, leaving a flat, or horizontal section, long. Bend 
this section sidewise V 4 " inside the first bends, and bend I 
back again Vz" inside these, so that a horizontal “U” to fit 
against the under side of the fuselage is formed. Cement J 
and bind with thread to the fuselage. Bend the lower ends 
of the struts horizontally for wheel spindles, slip on the 
wheels, and hold them in place with a ball of cement on the j 
end of each spindle. 

To attach the wing, loop a rubber band under the 


















































































































































JUNIOR PLANES 


fuselage, stretch the ends above, and slip the wing through 
these loops. 

To lay out the propeller, smooth the blank, draw cross 
lines ly/' from the ends on the faces, and draw diagonals. 
On the edges draw lines tapering the thickness off one third 
at the ends. Pare down to these lines, and saw out the cem 
tenwidth pieces. Be sure to leave about V/' thickness for 
the hub. 

Whittle the inner faces of the blades, hollowing them 
about in the width. They also curve backwards length- 
wise because of the tapering back of the front, and this 
spoon shape must be carefully followed. When the backs 
of the blades are finished, do the fronts, making the thick¬ 
ness iV". Round the ends, hollow the back to about one- 
third the thickness of the blank, and complete the blades. 

Push the propeller shaft through the hub, bend a hook, 
and force this into the front of the hub, where it is cemented. 
Bend the motor hook, and install the shaft in a bearing made 
of heavy tin, brass, or aluminum, which is cemented and 
bound to the nose of the fuselage. 

Make an ‘'‘'S^’-hook to clasp the tail post. 

To install the motor, tie a nail to a piece of string and 
drop it through the fuselage from nose to tail. Tie the 
string to the rubber loop, and pull it through. Loop it 
over the hooks. 

Glide the plane to find the wing position. When this 



MONOPLANE 






























90 


JUNIOR PLANES 


has been located, try a flight with the motor partly wound 
up. So high-powered is the little machine that it will go 
up in a half-loop and fly upside down for some distance. As 
this maneuver is dangerous for the plane, the propeller must 
be pointed downward a little by looping a fine wire around 
the upper side of the fuselage and under the shaft, so as to 
raise the hook. With proper adjustment, and hand launch¬ 
ing, the plane will sweep down almost to the ground, and 
then, as the power of the motor decreases and the down¬ 
ward pull of the propeller lessens, it will gain altitude and 
circle around. 


3 


A FUSELAGE LOW^WING MONOPLANE 

A flying model plane that climbs well is likely to be 
a poor glider, and the good glider may not gain much ele' 
vation. For a long flight, a distance glide is needed, since 
the rubber motor can keep the propeller pulling for only 
a short time. If the motor while working can get the plane 
high in the air, and the ship can glide in a satisfactory way, 
it may take considerable time to reach the ground, and if 
it should fly over a warm spot where the air is rising, it 
might actually gain elevation after the propeller has stopped 
turning. 

In this plane the stabilizer is placed some little distance 

above the level of the wing. 

For wing spars, get three pieces of by 3 % by 20" balsa; 
for the stabilizer, one piece 30" long; for ribs, fuselage sides, 
tail, etc., one piece re by 2 V 2 by 24"; for propeller, one 
piece Va by 114 by 10"; for propeller shaft, hooks, etc., 
three hairpins; for landing gear, 16" of music wire the size 
of mechanical pencil leads; for wing covering, Japanese rice 
paper, or other tissue, 8 by 24"; for the motor, 5 ft. of l/s" 
flat rubber; also two glass beads, a rubber band, F/z of 
91 


92 


JUNIOR PLANES 


rubber tubing for the hooks, ambroid cement, wing dope, 
and bits of light cloth. 

Draw the outline of the wing on a board. Make the 
rib pattern of cardboard by drawing the Va' sauares through 
which to sketch the outline. Trace the ribs and cut them 
out with a razor blade. The eight ribs, held side by side, 
can be notched at the same time. Glue in the front and 







































































A FUSELAGE LOW-WING MONOPLANE 93 

trailing spars, and then the upper spar. When dry, cut the 
front spar in the middle, score the trailing spar for breaking 
it, and cut the middle spar off flush inside the center ribs. 

Cover both halves of the wing with the tissues. Coat 
the under side of the trailing spar with cement and glue 
one edge of the paper to it. Then bring the tissue around 
the leading edge and back, gluing it to the ribs and the up' 
per side of the trailing spar. Trim the edges with a ra 2 ,or 
blade, and dope the wing. 

The two halves of the wing are joined with two splice 
blocks Vs" thick. The trailing block comes to a blunt point 
at the bottom, and the lower edge of the front block slopes 
the same way, but is notched at the side to join the left 
wing, so that this side will have a greater incidence angle 
than the other, to overcome the tendency of the motor to 
revolve the plane in the opposite direction from the propeh 
ler. The ends of the plane are IV2" higher than the center, 
forming the dihedral angle. Glue a floor to the tops of the 

splice blocks, by Vs by 314". 

Cut the two fuselage sides from A balsa, notching 
them by at the top of the curve, and at the bottom, 
for struts. Notch the sides at the top for the stabilizer. 
Glue a tV by V?, by 13" floor to the lower edges of the sides. 
Add the two cross struts, and the fuselage is complete. 

The bearing is made from a hairpin. Bend the end 
around a brad, squeezing the wire together with pliers, and 


94 


JUNIOR PLANES 


V 2 " from the hole bend the wires apart. Bend them parallel 
again A" farther on, and bend the bearing end up at right 
angles. Cement the wire inside the nose of the fuselage, 
holding it down in the comers until dry, and reenforce with 
3 W" square blocks glued above. 

For the landing gear, bend the music wire into a “U” 



with a square bottom about wide. Bend this loop at 
right angles to the legs, Vi" down, and bend the legs out 
until at a point from the bend they are 5" apart. Bend 
them back for skids, turning them up a little at the ends, 
and cut to a length of Cement to the under side of the 
fuselage nose, and glue a strip of cloth over the loop, up 









A FUSELAGE LOW-WING MONOPLANE 95 

the sides of the fuselage, and with the comers folded over 
the upper edges of the sides. 

The rear hook is also made of a hairpin, and the two 
legs are cemented outside the tail end of the fuselage. 
The stabilizer is built over a pattern on a board, as was 


the wing; but unlike the wing, it is flat, with ribs square. 
It is covered on the upper surface with tissue, which is cut 
out in the center, so that the stabilizer can be glued in its 
notches in the fuselage. 

The tails are tV by 1 by 3", with the upper comers 
rounded a little and the edges sanded sharp. These are 



96 


JUNIOR PLANES 


then glued inside the fuselage, sloping backward a little. 

To carve the propeller, draw diagonals on the faces of 
the blank and whittle the insides of the blades, hollowing 
them somewhat. Carve the outsides of the blades, sand 
them until light can be seen through them, and force hairpin 
wire into the hub. Bend the wire end at right angles, and 
cement. 

The shaft hook should be iVi' behind the bearing. 
Make an ‘’'S'^'hook for the rear end of the motor, so that a 
winder can be used. Slip rubber tubing over both hooks. 

Use two double strands of Vs'' rubber for the motor. 

Glide the plane until it balances well, and then try it 
out under power. If the rubber is stretched out to double- 
length with the winder before twisting, about twice as many 
turns can be given it without breaking. 


4 


THE SEAGULL TRACTOR 

This little monoplane, with its tips sweeping back like 
the wings of a soaring seagull, is a splendid performer. The 
writer’s model, with its rubber motor twisted by turning 
the propeller, and launched from the hand, rose some sixty 
feet in the air, made five or six large circles, and came down 
about 350 feet from where it started. If a winder had been 
used, the plane probably would have stayed aloft twice as 
long. 

The wing spread is 20", the fuselage length is 15", and 
its weight, complete with the motor, is 14 oz- 

For materials, have a strip of tV" balsa 1 by 24"; for 
landing gear, etc., 40" of A" music wire; also wing dope, 
ambroid cement, mucilage, fine thread, 8 ft. of Vs" flat rub' 
ber, a small bit of camera film or other thin celluloid, and 
rice paper 8 by 20". 

The first step in building the plane is to lay out the 
pattern of the fuselage plan on a board or table top. Draw 
a center line 15" long, and at the tail make marks le" each 
way from the center. A foot from there locate marks Vi 
each side of the center. Draw lines connecting, which rep' 


97 


JUNIOR PLANES 


98 

resent the outsides of the longerons, and draw cross lines 
every 2" for the struts. 

Push several pins in to hold the longerons in place, but 
for the time do not do anything with the curved nose. 

Now lay a ruler on the veneer, and with a razor blade 
cut four strips tV^ wide for longerons. Trim them to 15^8" 
in length. Ambroid one end of a pair, and lay the pieces 
inside the pins on the plan. Cut from the scraps x’e by 




















































THE SEAGULL TRACTOR 


99 


To" struts to fit snugly between the longerons, and ambroid 
them in place. When dry, cement the nose and pin the 
longeron ends together. Fit in the remaining strut. 

The upper fuselage frame is built on top of the lower, 
with a sheet of waxed paper between to keep them from 
sticking together. When taking the frames apart, spring 



the pins outward, slip a thin knife blade between the frames, 
while raising up the free ends with the fingers, and gently 
pry apart any stuck places. In the same way loosen the 
lower frame from the board, but press it down flat again. 

Lay a block on the lower frame, Uii" from the 
tail end. Tack nails at each end to keep it from shifting, 
and pin the upper frame on top, directly above the lower. 
Cement the tail post in, and add the struts. Be sure that 



























100 JUNIOR PLANES 

the tail post and struts are vertical. When dry, remove the 
blocking. 

Glue square balsa pieces across the corners of the 
bulkhead, which will brace the assembly and prevent the 
frames from racking to one side or the other. 



Now cement the nose ends of the longerons to a Vs by 
V 4 by Vs"" nose post. Put three wraps of fine thread around 
them while drying. Be sure that the nose centers well, for 
if it points sidewise, the propeller will drag the plane around 
in short circles that waste the power and shorten the flights. 

For the shaft bearing, push a brad through the nose 
post V 4 '' from the lower edge, inclining it upward toward 
the inside. Trim the lower end of the post back Drill 












THE SEAGULL TRACTOR 


101 


a piece of celluloid Vs by V 2 ” long, and cement it to this 
sloping part of the post. 

Cover the fuselage with rice paper. Cut a strip for each 
side and glue it to longerons and struts with mucilage or 



thin library paste thinly applied. Be sure it sticks well at 
all points, for the paper sheath must brace the frame to 
keep it from twisting. The ends of the sides must be left 
open for getting the motor in and out. 

Trim the edges of the paper smooth with a razor blade. 























102 JUNIOR PLANES 

and sand the comers of the nose and tail until round. 

For the propeller use a piece of balsa Yi by 1 by 8". 
Draw diagonals on both faces, and push a pin squarely 
through where they intersect. Draw lines parallel with the 
edges, centering on the width. Vs" apart, for the hub. Rip 
along the diagonal lines to the hub, and carefully chisel 
the waste pieces from it. 

Carve the blades to thickness. Then work out the 
backs until they are hollow, sanding them smooth. The 
fronts are then carved rounding, and are sanded until light 
can be seen through them from the tips nearly to the hubs. 
Trim the comers round, file the hubs to curve smoothly 
into the blades, and cut them away to a front-and-back 
thickness of Vs". Round the comers of this last cut. 

The shaft is e?"' piano wire cut 4" long. Bend a motor 
hook on one end. Push the straight end through the bear^ 
ing, from the inside, thread over it two or three small wash- 
ers, and put it into the propeller hub. Bend a small hook on 
the front end, to be pushed into the hub and cemented. 

The tail hook is a loop of wire put around the tail 
post; but it must not be cemented until the tail is in place. 
Bend an “S’'’"hook from the music wire, so that a winder 
can be used on the motor. 

Use six strands of Vs" mbber for the motor, with the 
loops about Vs" longer than the distance between the hooks. 
Tie the ends with thread. 



THE SEAGULL TRACTOR 













104 


JUNIOR PLANES 


To protect the rubber from being cut by the hooks, 
wrap the wire with thread or slip on short pieces of small 
rubber tubing, such as can be purchased at a model supply 
counter. 

To build the wing, draw a pattern as was done for the 
fuselage. Make a rectangle 3 by 20", dividing it in halves 
lengthwise. Measure along the leading edge 1" from each 
end, and square back from the ends 2%", showing the length 
and angle of the end ribs. Mark a point V/s" back from 
the leading edge at each end rib, showing where the trailing 
spar butts against it. Also locate the ribs, which are 3" 
apart, starting from the center. 

For spars cut two strips wide from the tV" veneer. 
Lay them in place, holding them with pins at the edges. 
Break the trailing spar at the center and cement it together 
at the angle. Butt the end ribs against the ends of the spars. 

Cut material for the other ribs Vs' longer than shown 
by the flat drawing. Roll a pencil on the under sides, which 
will curve them, the amount depending on the pressure. 
Notice that most of the curve is in the front ends, extending 
about one-third the way back, while the rest of the rib is 
nearly straight. Naturally, the center rib, being the longest, 
has the deepest curve. 

Build the tail next. The trailing edge is mitered against 
the leading edge, and the lower piece butts between these 
two. 


THE SEAGULL TRACTOR 


105 


Attach the tail by cementing the lower piece to the up¬ 
per side of the fuselage. 

For the front wing stirrup, cut a piece of si" music wire 
2" long cind, centering on its length, bend into a square “U” 

wide. Bend the legs back and upward Vs" from the first 
bends, and V 4 " from these bend into backward hooks. Cut 
off the remaining ends. Cement the hooks over the tops 
of the leading wing spar, at the center. 

The back stirrup is Vs" wide and Vs" high. 

To attach the wing to the fuselage, pass a strand of iV' 
square rubber through one of the downward loops of each 
stirrup. Pass the rubbers under the fuselage and thread 
through the other loops, tying them there. Handle the 
plane carefully, for the parts are easily broken. 

The pull of the rubber may warp the wing out of shape; 
but this is easily remedied by slipping wedges under one 
end or the other of the leading stirrup. The exact amount 
of “wash” to oppose the motor can be obtained in this way. 

Draw the landing-gear pattern on a board and drive in 
nails where the wire is to bend. Use ^ 1 " music wire, twist¬ 
ing the ends together at the back clip. Use pliers to get 
sharp bends, so that the straight parts will not be sprung 
into curves. Remove the wire from the form, bend it at 
the axle points, and twist the stirrups vertical. Cement the 
stirrups to the fuselage, the front forward of the bulkhead, 
the rear about 5^8" behind it. 


106 


JUNIOR PLANES 


Each wheel is made of two 1" circles of writing paper, 
cut radially to the center at one point, with the flaps glued 
under to make the sides into cones. Glue the edges to- 
gether for the rims. Thread a straight 155 " wire axle 5" long 
through the wheels, bend the ends up, and coat with cement 
to prevent the wheels from working off. Tie the axle to 
the struts with thread, and ambroid. 

Bend a tail skid to push into the lower end of the tail 
post. 

Try the plane for gliding with the wing about AYi' back 
from the nose. If it nosedives, move the wing forward, 
and if it stalls, move it backwards. When a flat gliding angle 
has been obtained, mark the position with a pencil. 

Now wind the propeller backward until a row of knots 
comes in the rubbers. Toss the plane lightly against the 
bree2;e. If it stalls, do not move the wing backward, since 
it is already adjusted for a good glide, but lift the back end 
of the propeller shaft with a fine wire fastened to the upper 
longerons and looped under the shaft. Adjust the shaft 
until a good flight is possible. 


5 


THE DIAMOND FUSELAGE R. O. G. PLANE 

The trim little Diamond Fuselage Plane gets its name 
from the lozenge section of its body. The construction 
gives strength, lightness, and neatness to the model, and 
provides good mounting for the wing and stabilizer. 

The materials needed for this ship are: For longerons, 
four pieces of Vs by Vs by 27" balsa, and one piece 20" 
long; for bulkheads. Vs by 21/2 by 9" balsa; for posts, one 
piece Vs by % by 2"; for wheels, one piece ^ by 1 by 4"; 
for the wing, two pieces Vs by A by 30"; for spars, and 
for ribs, a piece 36" long; for tail, one piece Vs by Vs by 13"; 
for stabilizer, one piece iV by 21/2 by 10"; for propeller, one 
piece % by iVs by 10"; for stirrups, propeller shaft, wire 
struts, etc., 28 of t* 6 music wire; for braces, 20 of sV 
music wire; also ambroid cement, 1 brads, thread, one 
piece of aluminum 3^2 by Vs by IV 2 "; rice paper 16 by 30". 

First make the three body bulkheads. Bulkhead “A” 
is 2 V 2 by 3V2". The side notches are centered between the 
top and bottom notches. Lay out a shape on a rectangle of 
Vs" balsa, with the grain running lengthwise, and saw out 
the notches with a coping saw, or cut them with a razor 

107 


108 


JUNIOR PLANES 


blade. Then cut the sides, next the inside, and finally the 

notches in the upper sides, 
which carry the false lon¬ 
gerons. 

The other bulkheads are 
made in the same way; but 
the side notches are nearer 
the upper notches than the 
lower. Notice the draw¬ 
ing of these parts. 

Make the nose post next. Cut the block I /2 by % by 1", 
and round the front corners. Carve Vs by Vs by V 4 ' notches 
in the sides, top, and bottom, to hold the ends of the lon¬ 
gerons, and make a hole from front to back. Vs by Vi', 

through which to put the 
propeller-shaft hook. 

The tail post is roundly 
triangular, Y/' wide at the 
front top, and curving 
back to a point Vs"' behind. 
Notch the upper and low¬ 
er comers. 

Lay the longerons together on the bench and mark the 
positions of the bulkheads and struts. Note that the bulk¬ 
heads are 5" apart, with “A"” 3" from the front end. Glue 
the side longerons to the bulkheads, carefully crack them at 








THE DIAMOND FUSELAGE R. O. G. PLANE 109 

''A,’’ and glue their ends into the side notches of the nose 
post and of the tail post. Fill the breaks with cement. 

Now add the upper and lower longerons, breaking them 
at ““A*” also, so that they will come straight to the nose 
piece. The upper longeron does not meet the tail post, but 



is 3" shorter than the others, the end being held with a trh 
angular false post detailed under the nose post drawing. 
This post notches around the side longerons, but is hob 
lowed underneath to give more room for the motor rubbers. 

Miter the ends of Vs by Vs balsa sticks to fit between 
the longerons at a point 3V4^" from the nose. Also put 
struts between the side and lower longerons under the false 
tail post. 



















no 


JUNIOR PLANES 


This construction gives a flat table for the mounting of 
the tail assembly, together with an angle back which wing 
stirrups can straddle. 

Trim the nose post to the taper of the fuselage when 
the cement is dry. 



For each wheel glue together two 1" squares of t's" 
balsa, with the grain of the pieces crosswise, to strengthen 
it. Cut the wheels 1" in diameter, and push a small 1" brad 
through each center, for a spindle. 

The axle is Vs by Ys by SVz" balsa, rounded on the ends 
and edges, and well sandpapered to reduce air resistance. 
Push the brad spindles into the ends. 




































THE DIAMOND FUSELAGE R. O. G. PLANE 


111 


The wire strut is a piece of music wire bent in the 
center, with a 2" length of balsa axle stock pushed over each 
end, cemented, and mitered to fit against the axle V 4 " from 
the ends. Tie and cement the wood struts to the axle, and 
carefully straighten the wire. Cement and tie the strut point 



over the nose struts of the fuselage, looping the thread 
around the longerons, as well as the struts, to distribute 
the landing shocks to the whole frame. 

It is not altogether necessary to brace the axle, but 
wire bent around the axle ends and brought up to the 
side longerons at bulkhead “A,” will help keep the wheels 
“tracking” when the plane takes off from the ground. 










112 


JUNIOR PLANES 


If better wheels are wanted, cement a Va' length of 
light metal tube in the center of each, which will prevent 
the spindle from crushing into the wood, making the wheel 
both off-center and wobbly. Such tubing can be bought 
at any store that carries model airplane supplies. 



HALF-5TAE>1LIZEIL 
4“ balsa, rounded on edges 


PROP 
DETAILS 
Cut blank 



PROP SHAFT 
BEARING 
Aluminum,4*X5^^ 



Motor hook 
covered with 
•M xii^^bearing rubbertube 
^ Prop beads 

PR.OPELLEB. SHAFT 
Cut wire 3long 


Inspect the fuselage carefully to see that there is a clear 
passage from end to end, beneath the side longerons, for 
the motor. If the bulkheads seem to interfere, trim the 
openings in the centers a little larger. Once assembled in 
the fuselage they are very strong, and can stand such re¬ 
duction in si 2 ;e. 

A good fuselage deserves a good wing, so make the glu¬ 
ing surface of this plane carefully. While the body holds 






























THE DIAMOND FUSELAGE R. O. G. PLANE 


113 


the other parts in position, and houses the motor, the wing 
gives the lift, and it can make or mar the performance of 
the plane. 

Outline the wing on a board, providing for 30" spars 
5 " apart from outside to outside. Square cross marks for 
ribs every 5". Drive brads or pins in the board to hold the 
spars. 

Cut the rib stock Wi' long. Lay the pieces on a mag' 
a^ine and roll a pencil on each, relieving the pressure as 
the trailing ends are approached. 

When the ribs are bowed Vi", miter the ends until they 
will lie flat when cemented to the upper sides of the spars. 

While the wing frame dries, shape the stabilizer. The 
leading edge tapers back from the center, and the trailing 
edge is tapered at the ends for IV 2 ". Round the comers, 
and sand the edges round. 

Give the wing a dihedral angle of 2*4", by breaking the 
spars beneath the center rib, filling the cracks with ambroid, 
and blocking the frame in position. 

The drawings show clearly how to shape the wire stin 
mps. It is important that the ends fit the wing spars accu' 
rately, so that they will not alter the dihedral angle, nor 
warp the wing. There must be no accidental twists in the 
wing. Cement them beneath the spars, and when dry, bind 
with thread and cement again. 

Cover the upper side of each half of the wing, cutting 


114 


JUNIOR PLANES 


the paper oversi2;e, and gluing it to the outer edges of the 
spars and the tops of the ribs. 

To cover the fuselage with paper, cut a strip, smear the 
outer edges of the longerons with glue, putting the paste 
on the bulkhead edges and struts as well, and stretch on the 
paper as lightly as possible. Trim to size when dry. The 
upper sides of the fuselage at the nose are left open, for 
convenience in handling the propeller shaft, and the lower 
sides at the tail are left open so that the "'S*”'hook can be 
drawn out to twist the rubbers with a mechanical winder. 

The tail is triangular, 3" wide at the base, and 6" high. 
Use Vs by Vs'' balsa for the uprights, with the upper ends 
butted and the lower ends glued in notches in the end of a 
t^ 6 by V 4 by 3" strip. 

Give one coat of dope to all paper covering. Prop the 
forward comer of the left end of the wing V 4 " high to give 
it greater lift in opposition to the twist from the motor. Glue 
a Vs by V 4 " stmt under the center rib of the wing to fur- 
ther stiffen it. 

Glue the trailing edge of the stabilizer to the tail post, 
and the leading edge to the longerons, but with a Vs by Vs 
by 1" block beneath it to give it incidence. Tie with three 
or four wraps of thread sewn through the balsa. 

Glue the tail base on top. 

To carry the end of the “S’'-hook, make a loop of fine 
wire around the tail post, and bend a light tail skid, with 


THE DIAMOND FUSELAGE R. O. G. PLANE 115 

the front end bent back on itself in a hook, forming a flat 
base to cement and tie to the under side of the lower lon^ 
geron. 

To carve the propeller, draw diagonal lines on the faces 
of the blank with parallel lines Va' apart at the center, for 
the hub. Flatten and slightly hollow the inner faces of 
the blades, then carve the front faces. 

Bend a hook on the propeller shaft, as shown, and push 
the other end through the hub. Bend it into a hook, and 
push the tip into the front of the hub. 

Drill a hole in the center of the aluminum bearing strip, 
and bend it around the nose. The ends clasp the back of 
the post. Cement it near the bottom of the hole through 
the post. 

Slip over the shaft a small washer and two glass beads, 
or other washers. Put the hook through the bearing, wrap 
it with thread or cover it with a short piece of rubber tub- 
ing. 

Make an “S'-hook for the tail, and install an S-strand 
i/s" flat rubber motor. 

Hold the wing on the fuselage with a piece of rubber 
looped through the stirrups and around the body. Pull the 
centers down and tie together with thread. When the 
proper position of the wing has been found by gliding, 
partly wind the motor and launch the ship against the 
wind. 


116 


JUNIOR PLANES 


The propeller in this position is adjusted for a slight 
downward pull to offset the front lift present when the 
plane is under power. If it is too low, raise the bearing, 
and if too high, lower it. A point should be found where 
the gliding position of the wing is correct for the power 
flight; but if not, raise or lower the hook end of the shaft 
by stretching a fine wire from the side longerons below or 
above it. 

To gain more elevation, block up the leading edge of 
the plane a little, and readjust its position. If the plane cir" 
cles to the left, with the rudder set straight, twist the wing 
flatter to decrease drag. 

For the best flights a mechanical winder must be used 
for twisting the rubber. 


6 


AN R. O. G. BABY COMMERCIAL PLANE 

Quite like a fulksized aeroplane is the Baby Commercial 
Plane. It has a wing spread of 30", and a fuselage length of 
27". When properly adjusted, it flies beautifully. 

The materials needed are these: For longerons and 
struts, four pieces of balsa *4 by Vs by 36"; one piece Vs by 
Vs by 12"; for landing gear and bulkheads, one piece Vs by 
Vi by 28"; for posts one piece Vi by 2 by IW'; for wing 
spars, two pieces of Vs by Va by 30" balsa; for ribs, one 
piece Vs by A by 48"; for blocks, one piece Vs by Vs by 8"; 
for propeller, one piece Vs by 1% by 10"; for wheels, one 
piece I'e by 1 by 4"; for propeller shaft, hooks, etc., 
music wire 7" long, and 7" of music wire, and two 1" 
brads; ambroid cement, thread, wing dope, rice paper 15 
by 30"; IV 2 "" of small rubber tubing; 16 ft. of Vs" flat rubber, 
for motor. 

First make two bulkheads, “A,” and “B.”. Cut a 2V8" 
piece of Vs by Vi" balsa, and with a razor blade divide it 
into two Va" widths, notching the ends Vs by Vs". Cut 
four longerons 27" long, so that the pieces trimmed off may 
be used for the upper and lower struts of the bulkheads. 

117 


118 


JUNIOR PLANES 


For bulkhead “B,*” cement V/s' struts across the sides al¬ 
ready made, the ends com¬ 
ing flush with the notches. 
Be sure the bulkhead is 
square. In assembling, the 
longerons fit into the cor¬ 
ner notches. 

Bulkhead ''A’’ has sides 2" long, with upper and lower 
struts IVs" long. 

The nose post is 1 t%" long. Use a piece of V 2 ' square 
balsa, cutting it down to a thickness of /e". Taper the thick¬ 
ness from front to back, making the front wide. The 
four notches are Vs by Vs by Va', made to receive the ends 
of the longerons. 

The tail post is long, le'' thick in front, and tapered 
back, with the trailing edge rounded. It is also notched in 
the ends to take the longeron tips. 

Draw a plan view of the fuselage on a flat board. Lay 
out the center line 27" long, with cross marks where the 
struts and bulkheads go. The first mark, starting at the 
nose, is V/' from the end; the next, 2 V 2 " beyond, and the 
next 3 V 4 '' farther on, and so on for the others, as shown in 
the drawing. The widths are also given there. Remember 
that these are outside dimensions. Drive brads in the board, 
just off the cross lines, with one outside and one Vs' inside, 
so that the longerons can be laid between. In this way the 








AN R. O. G. BABY COMMERCIAL PLANE 


119 


lower ones are held firmly in position during gluing up. 

Put cement on the ends of the two lower longerons, 
and in the notches of the nose and tail posts. Push the Ion' 
geron ends into the notches, slip a Vx block under the tail 
ends, and a block under the nose. Be sure the posts are 



Prop bearing, cemeirted 
and tied to nose block. 


FUSEUGE DETAILS of RO.G. 
BAbY COMMERCIAL PLANE 


vertical, and that the centers, or rather the parts of the Ion' 
gerons under bulkhead “B,” rest on the board. 

Now cement the bulkheads in place, propping them up' 
right until the glue is set. 

It is now easy to glue the upper longerons into the 
notches in the posts and bulkheads. Cut a nose strut to fit 
between the lower longerons, and one of equal length to 































120 


JUNIOR PLANES 


glue between the upper ones. In the same way cut struts 
to go about midway between the tail posts and bulkhead 
“A.” Also fit vertical struts between the upper and lower 
longerons. When the cement is dry, bend the nails in the 
board aside, and gently lift the fuselage from the form. 

Now bend the propeller bearing. Make an eye in the 



-^7"- 

q1** 



o:i 





—I- 

- 


UYOUT FOR UPPEIL&.LOWEIL LONGERON A55EMBUE5 





1 


i lU 


N05E 1TAILP05T5 
Cut fc?ur notches ^ 
in nose post. L 
g-x across ends of 
tail post. 


PROP SHAFT 
BEARING 
Cut wire li 


Tie and glue struts 
to longerons and fus¬ 
elage struts, cen¬ 
tering y from nose. 



^-•-Section 
LANDING GEJOLABSEMBLY 


center of the heavy wire, by bending it around a brad. With 
small pliers bend the ends out behind the eye, and then 
back again, so that they will fit against the nose block when 
put in place as shown in the assembly drawing of the 
fuselage, that is, with the eye below the nose, and the ends 
diagonally across the sides. Bind with three or four wraps 

























AN R. O. G. BABY COMMERCIAL PLANE 


121 


of thread, and ambroid. When dry, carefully bend the eye 
until it is parallel with the nose post. 

No tail hook is used. Instead, loop the fine wire around 
the tail post, so that it projects Vs' in front, and twist the 
ends behind, cutting off the surplus. Ambroid it at a point 
near the top. 



WINO TmAL &C DIHEDRAL ANGLE 



3LOCK DETAIL 
Eron-t block is 
X,'rear,gf. Thickness, 


WING CENTERELOCR5 

WING DETAILS of HO.G. 
BABY COMMERCIAL PLANE 


It is not necessary to cross'brace the fuselage to resist 
the twisting effect of the motor, since the paper covering 
is enough. 

The landing gear is next. For each wheel cut two 1" 
squares of tV veneer, and glue them together with the 
grain running at right angles. The wheels are 1" in diameter. 







































122 


JUNIOR PLANES 


The axle is Vs by W by SVi", with the edges and ends 
rounded. 

Push a 1" brad through the- center of each wheel for 
a spindle. Ambroid the brad under an end of the axle, 
and wrap with thread, which is also glued. 


lO" 


- 2 |- 




STABIUZEE. 



Trame of 
balsa, 
on one side, L 
round, the 
comers of 
the bare 
side 


j- Frame b balsa. Cover underside with paper. 

I ^ 

[■f^Fine wire^ 

J^2.beads, 

TAIL 




PROP SHAFT ADJUSTMENT 


a block under trailing 
edge of stabilizer 



TAIL ASSEMBLY 


PHOPELLEH CAHVING 
Size of blank, |“xl|‘klO* 


The struts are made with rounded edges, and cut 6" 
long. Glue and tie them to the fuselage at the nose struts, 
and add a piece across the top for reenforcement. Glue and 
tie the lower ends to the axle. This is easily done if the 
thread is sewn through the ends with a needle, just as cloth 
is sewn. 

The tail skid is a piece of light wire pushed into a hole 














AN R. O. G. BABY COMMERCIAL PLANE 


123 


in the tail post punched with a needle, and bent into a 
broad hook. A touch of cement will hold the skid tight. 

In making the wing, it is well to draw the outline on a 
board, and to hold the spars with a few brads or pins 
driven each side. Cut the ribs 5i'5" long. Lay them on a 
14" stack of newspaper, and roll a pencil over one side, 
pressing down firmly at one end and gradually decreasing 
the pressure. This gives camber to the wing. The curve is 
14" deep at a point about one'third the way back from the 
front. Trim the rib ends so that they will rest flat on the 
tops of the spars, where they are cemented. 

Gently break the spars at the center rib, block the 
frame with the ends 214^^ above the center, ambroid the 
breaks, and let dry. 

Make the center blocks. These are cut from Vs by W 
balsa, and the upper edges are notched to fit under the 
wing spars, to hold them at the dihedral angle. The rear 
block is cut down to A" in width, which gives the wing an 
angle of incidence when in place on the fuselage. 

Cover the upper surface of the wing, one^half at a time, 
with rice paper. Cut the paper large enough to leave finger 
holds at sides and ends. Glue to the front edge of the lead' 
ing spar, coat the tops of the ribs, draw the paper smoothly 
over them, and finish by cementing to the trailing edge of 
the plane. Cover the other half in the same way, and trim 
the paper to the frame. 


124 


JUNIOR PLANES 


Glue a Vs by V4'' balsa strut between the blocks, beneath 
the center rib, to prevent their being pushed over in flight. 

Cover the fuselage with paper, from nose spars to tail 
struts. The ends are left open, so that the rubber motor can 
be adjusted and wound. Cover one side at a time, trimming 
the edges smooth before the next side is covered. 

The stabilizer frame is flat, with straight ribs glued on 
the under side and covered with rice paper. 

The tail is a right triangle, V^/a on the base and 6 " in 
height. Notice that the upright pieces are Vs'" square balsa, 
with the lower ends glued in notches in the end of a base 
streamlined from Vs by y% balsa. 

Give all paper one coat of wing dope. Prop the wing 
with the leading comer of the left end V4" higher than the 
other, giving the wing “wash’’ to resist the propeller torque. 

Cement the stabilizer to the top of the tail end of the 
fuselage, with a re" block under the trailing edge. Cement 
the base of the tail to its center. 

The wing is held by a scrap of rubber band strecthed 
around the center stmt and the body. The flying position 
is about 9 " back from the nose. 

The propeller is carved with the blades thick, haw 
ing the ends rounded at the comers. Cut out the hub Vs" 
at the back. 

Bend the hook on one end of the propeller shaft, and 
push the other through the propeller hub. Bend the end 


AN R. O. G. BABY COMMERCIAL PLANE 


125 


into a small hook to push into the wood. Slip on a washer 
and two glass beads, or other washers, and pass the hook 
through the bearing. Cover the hook with rubber tubing. 

Make an “S”'hook for the rear end, and put tubing on 
the motor hook. 

Use eight strands of rubber in the motor, making the 
skein long enough to sag a little between hooks. 

The plane is now ready for flying. Glide it until the 
wing is properly adjusted. If it settles back on the tail, 
move the wing backward; but if it nosedives, move the 
wing forward. 

For a trial flight, wind the propeller backwards until 
a row of knots appears, and toss it lightly into the breeze, 
pointing about level. If it dives, adjustment of the propeh 
ler is very likely necessary. 

It will be seen that the propeller is lower than the tail 
hook, so that it pulls downward a little. With the propeller 
shaft inclined downward at the proper angle, the power 
flight will be made with the wing in a good position for a 
long glide. 

It is easy to adjust the propeller by stretching a fine 
wire above or below the shaft, tying the ends to the fuselage. 

If a winder is used, long, beautiful flights are possible 
with this model. 


7 


BUILDING THE FREIGHTER 

The Freighter is just what its name indicates—a reliable 
flier, strongly built, with a good landing gear that takes up 
hard landing shocks. It rises quickly to a fairly high altitude, 
and the motor unwinds practically at its “ceiling,” leaving 
the plane high for a slow glide to earth. 

These materials are needed for the plane: For the wing, 
four pieces of balsa Vs by Vs by 30", used for spars, and for 
ribs, balsa 1 by 46"; for stabilizer and tail, one piece 
Vs by Vs by 24", and one piece 30"; for longerons and struts, 
two pieces of balsa Vs by Vs by 24", and a piece 30" long; 
one piece Vs by by 24"; for landing struts and axle, three 
pieces of bamboo by Vs by 12"; for wheels, balsa x^e by 
1 by 4"; for the propeller, balsa 1 by 1% by 12 "; for propeh 
ler shaft, hooks, etc., ex'" music wire 6" long, and # 2 " wire 
8" long; aluminum x^e by je by IV 4 "; also rice paper 15 by 
30", and 8 by 20"; pins, brads, thread, ambroid cement, and 
dope. 

First shape the ribs. Carefully draw the pattern on thin 
cardboard, using a rectangle % by 5" for a base. The upper 
curve comes to full height 2" from the landing end, and 


126 


BUILDING THE FREIGHTER 


127 


slopes gradually back, reversing a little as it nears the traih 

ing end. The under curve, 
being more nearly the arc 
of a circle, reaches its high 
point a little behind that of 
the upper curve. It reverses 
and is even with the base 
line for V%". This form of 
curve gives a fair amount of 
Hft to the wing, yet smooths the air currents as they leave 
the surface, reducing the eddies. 

When the pattern is well shaped and cut out, clip Vs" 
square notches above and below, and in the nose, with a 
fourth notch at the back end by Vs". Trace nine ribs 
on the iV" stock, and cut them out with a razor blade. 

Cut four spars to length, sanding them smooth. The 
tr ailin g spar is thinned with sandpaper to a thickness of 
ifW". Lay them side by side to mark the rib positions cem 
tering 3%" apart. 

Glue the leading and trailing spars to the ribs, putting 
glue on the notches and spars as each one is added. Be sure 
the frame is held square with pins or brads until dry. Ce- 
ment the upper spar in its rib notches, and add the lower. 
This construction is strong and light in weight. 

The wing has a dihedral of IV2". To make the bend, 
clip the upper spar at each side of the center rib, clean out 









128 


JUNIOR PLANES 


the notch, crease the other spars at the center so that they 
will make sharp angles, and draw the open ends of the 
upper spar together. If this does not give enough depth to 
the dihedral, trim a little more from each cut end. Glue 
the cut ends together in the rib notch, and tie with a few 



turns of thread sewed through the rib with a needle. 

Quite a little time is needed to cover the wing with 
paper, and for this reason it is easier to use a slow^-drying 
adhesive, than the celluloid glue. Mucilage, library paste, 
or even paste made from flour (which is very light when 
dry) is good. Cut four strips of paper 5%" wide. 

Spread paste thinly with the finger tip along the front edge 














































BUILDING THE FREIGHTER 


129 


of the wing, lay one sheet of paper over the top, and press 
the edge smoothly along the spar, drawing it lengthwise. 
Apply paste to the ribs, and to the back edge of the trailing 
spar, and draw the paper smoothly down. Cover the other 
half the same way. 

Paste must be applied to the under edges of all ribs, 
and the paper pressed well against them. Pull lengthwise, 
but not crosswise, as this would draw it away from the 
under camber. 

When the paste is dry, give both surfaces a coat of 
dope, and trim off all projecting paper, smoothing the edges 
lightly with fine sandpaper. 

Nothing is said about ‘wash,” or twist in the wing to 
offset propeller torque. If the builder wishes to make sure 
of such twist, he may block the wing in position while the 
dope is drying; but without any blocking there is likely 
to be enough warp to one side or the other, and the propeh 
ler can be carved right' or lefuhanded, to suit. 

Clips must be made to hold the wing to the fuselage. 
Use 32 " music wire. Bend a Vs" hook on the end of the 
wire, to clasp the upper side of the front spar. Leaving V 2 
for the vertical leg, bend the wire at right angles. Bend an 
upward loop about N' high at the center of the horizontal 
part, continue the latter, and make the vertical leg and 
hook that completes the cHp. Cut off the surplus wire. 

The rear clip is 1%" wide and V 4 " high. 


JUNIOR PLANES 


130 

Hook the clips over the leading and trailing spars, ce^ 
ment them, and bind with thread, cementing once more. 

The stabili2;er spars are Vs by Vs by 12", sanded with 
rounding comers. Cut the ribs 3 Vs"' long and roll them on 
the under sides with a pencil, full length, curving them to 


-Tail covered on 
one side 



^ Lcwp rubber binder around center 
point of clip and tie ends beneathihe 
fuselage Similar binder at trailingedge 


-landing struts are bound to fuselage struts 

THE.WT.D.FmGtrrER 


the arc of a circle with a depth of camber of V4'- Miter 
the ends, and cement them to the spars. 

Cover the riboside with paper, but do not dope. At the 
most, only shrink the covering with a light spray of water, 
as the frame may be warped out of shape if varnish is used. 

Build the triangular tail of Vs" square balsa, and cover 




BUILDING THE FREIGHTER 


131 


one side with rice paper. Mount this on the center line of 
the stabilizer, cementing it and pushing a pin through the 
trailing spar of the stabilizer into its vertical spar, and 
through the leading spar into the forward point of the tail. 

In building the fuselage, first draw a center line for the 
top frame Thyt long. Draw lines across it for the strut 
positions, one 2" from the nose, the second V-/! behind it, 
and so on, as in the drawing. Cut the struts to the lengths 
shown, and lay them in place, with a pin through the cem 
ter of each into the board. 

Cement the ends of the two Vs" square longerons, tie 
them together with thread, and lay them on the board, put' 
ting a pin through the joint to hold it at the nose point. 
Apply cement to the ends of the struts, and the parts of the 
longerons that touch, and draw the longerons together 
against the struts. Hold the tail ends with pins outside them 
until dry, when the frame can be raised from the board by 
slipping a knife blade between them. 

Cut a tail post from the Vs by fd’ material, Va long, 
which is cemented to the top frame. 

The bearing strip is next. Cut a piece IV 4 " long, and 
drill it Vs" from one end for the propeller shaft. Bend Vs" 
of each end back, and curve the strip outward with the 
crown at the bearing hole. Bind this bearing hanger to the 
nose of the top frame, and the completing of the fuselage 
is in order. 


132 


JUNIOR PLANES 


The depth of the body is 2". Cut a wooden block to 
this width. Lay the upper frame upside down on the board, 
and cross it with the block, which is clamped or tacked in 
this position. 

Now hook the end of the Vs by A" longeron under the 
bearing hanger end, cement it, and bind with thread. Draw 
the other end down to the tail post, where it is cemented 


5 xgx 234 longerons form top frame - 


Tail post - 



^Nose post 


lower longeron-^ 


DIAGRAM OF BODY ASSEMBLY 





—3|- 



-t 





PIAN, I SIDE ELEVATION of FUSELAGE 



T& 


NOSE POST (Aluminum) 



SECTION THRUA-A 






































BUILDING THE FREIGHTER 


133 


and pinned. Be sure, after this, that the heavy longeron is 
exactly above the center of the upper frame. 

Cut struts to fit between the longerons, with the same 
spacing as those of the upper frame. Ambroid them well, 
and let them dry before taking the body up. 



Cover each side of the fuselage separately with paper, 
gluing it to the longerons and ribs or struts. The nose and 
tail must be kept open for inserting and repairing the mO' 
tor. 

Give the skin one coat of dope. 

The landing struts are bent by steaming them over a 
kettle spout, with the glossy side out, or they can be formed 
by soaking in water all night and pinning them in position 
until dry, or by holding them, while wet, over a flame, 
bending them a little at a time. 

Cut the pieces about 914" long after bending, and tie 
them together to form an '''X,’’ with the crossing 2 V 2 from 
the upper ends. Straddle under the fuselage, and bind to 





















134 


JUNIOR PLANES 


the front stmts, being sure that the bent ends are on a line 
at right angles to the body. Cement the bindings. 

Cut the axle lOVi' long and cement and bind it to the 
bamboo stmts. 

For the wheels, glue two 1" squares of tg" balsa face to 
face with the grain at right angles. Draw 1" circles and 



cut out the wheels. Push a small brad through the center. 
of each, for a spindle, which is cemented and bound to the 
axle end with thread. 

To carve the propeller, smooth the faces of the blank, 
and of course see that the edges are square. Draw a line 



BUILDING THE FREIGHTER 


135 


across the center of each face, and one 2" from each end. 
Draw lines from the end lines to points 14'" each side of 
the center, and saw along them. Carve the insides Vs" 
hollow at the widest parts, and work down the outsides of 
the blades, leaving not more than iV' at the ends. 

Shape in around the hub, and cut away the back about 
14", tapering to the full width of the blades. 

This does not make a true^pitch propeller, but it is very 
efficient for this plane. 

Bend the propellenshaft hook, thrust the straight end 
through the propeller hub, bend a hook in it, and push it 
into the hub front, where it is cemented. Make two or 
three aluminum and celluloid washers, slip them over the 
shaft, and put the hook through the bearing. 

Make an “S”'hook, and loop a hairpin or other small 
wire around the tail post near the top, to take the hook. 

Use ten strands of 14" flat rubber for the motor, allow¬ 
ing very little slack between hooks. Slip it through the 
fuselage, and install. 

The tail-and'Stabilizer assembly is cemented to the top 
of the body, with a 14" block under the trailing edge of 
the stabilizer to make it negative. The hollow side, of 
course, is up. A pin pushed through the leading spar into 
the upper longerons, and cut off flush, makes the assembly 
solid and strong. 

The wing position is about 6" from the nose. Tie a 


136 


JUNIOR PLANES 


rubber band around the fuselage here, and another 5" be- 
hind. Put the wing in place, and lift the rubbers over the 
center loops of the clips to hold the wing. 

The plane is ready for test glides, and two or three ad¬ 
justments of the wing fore and aft should be enough to get 
a long, flat glide and a three-point landing. To protect the 
tail end of the fuselage push a pin into the under edge, bend 
it back, and cut off the head. 

Now wind the propeller by hand until the first row of 
knots shows, and cast it into the wind. If it stalls, or climbs 
at too steep an angle to be efficient, raise the hook-end of 
the propeller shaft by looping under it a fine wire, to be 
tied to the upper longerons. A little adjustment of this will 
keep the plane from stalling, without spoiling the final glide 
by pushing the wing back on the fuselage. A word of cau¬ 
tion, however: Do not point the propeller too steeply 
downward at first or the ship may go into a bad nose dive 
and crack up. A stall will seldom “take a crate to pieces,'’ 
but a bad nose dive is almost certain to do so. 

You will find that the plane flies well if only wound by 
hand; and actually it will perform well with eight strands 
of rubber. But the ten are needed if a winder is used. 


8 


THE ENDURANCE TUBE MONOPLANE 

Designed for endurance flights and trim appearance, the 
Endurance Tube makes good in every respect. It looks very 
simple to build, and in fact is; but careful workmanship is 
needed throughout if the best flights are to be had with the 
finished ship. Every little refinement will add both to per' 
formance and appearance. 

Purchase these materials for the plane: For the tube, 
one piece of soft balsa Vs by 1*4 by 36"; for caps, one piece 
% by 1*4 by 6 */ 2 "; for propeller, one piece 1 by P/i by 15"; 
for wings, etc., one piece Vs by 24"; ih" music wire 32" long; 
for bearing, aluminum 3*2 by t 4 by 1"; light wing tissue 
paper, 16 by 24"; also ambroid cement, wing dope, fine 
thread, pins, twine, two celluloid washers to fit the propeller 
shaft, 4" of 3 * 2 "" rubber tubing, and twine. Two IV 2 " wheels, 
of celluloid or balsa, are needed. If of balsa, use three pHes 
of tV' veneer, cut from a piece 1*4 by 9", and glued together 
with the grain of the center ply running at 60 degrees with 
the outer layers. 

First of all, cut the wing stock to width, using a ruler 
or other straight edge to guide the razor blade through the 
137 









THE ENDURANCE TUBE MONOPLANE 


139 


sheet balsa. Make two spars Va" wide, and seven ribs Wi" 
long and tV" wide. Seven other ribs 4V4" long are also 
needed. 

Sand all these pieces on all sides, rounding the comers 
a little. To avoid breaking them, rest them on the bench 
top, and stroke from the center out, so that the sandpaper 
cannot catch the ends. If the edges of the parts are very 
irregular, they should be planed straight, using a block 
plane. 

Draw on a board a full'si 2 ,e plan of the wing. Near each 
rib joining with the spars drive pins along the leading and 
trailing edges, and lay the spars in place. Then glue the 
ribs between, making butt joints. If you have trouble keep' 
ing the ambroid from cementing the frame to the board, 
slip scraps of paper under the joints, or cover the plan with 
waxed paper before driving in the pins. 

While the frame dries, camber the upper ribs. One by 
one lay them on the bench and roll them on one side with a 
pencil, gradually increasing pressure from the trailing ends 
to the front ends, so that the deepest part of the curve is 
about one'third of the way from the front ends. Avoid 
“bumps” in the finished ribs, since they decrease the lift of 

the wing and increase drag. 

Now Hft the frame, clean off blobs of glue and any paper 
sticking to the joints, and lay it again on the bench with 
a spar even with the edge. In this position it is easy to 






PROPELLER. 












































THE ENDURANCE TUBE MONOPLANE 


141 


sand the outer comer of the upper side. Taper from the 
under edge to the upper inner edge, thus making the spar 
triangular in section, eis shown in the drawing. Do the 
same with the other spar. 

Once more lay the frame in place over the plan, between 
the pins, flat side up. ^A/ith the razor blade slice off the 
ends of the cambered ribs, so that they will lie flat, and glue 
them to the spars above the straight ribs, sticking pins 
through the ends to hold them. Cut a Vs" square block Vz" 
long for each rib, gluing it to reenforce the curved tops. 

Let the wing frame dry thoroughly before disturbing it. 
Then, pressing the thumbs at the center of each spar, and 
pulling gently upward underneath with the fingers, break 
the spar. Fill the breaks with ambroid. Block up the ends 
2 " above the center, forming the dihedral, and to give extra 
lift to the left wing, to offset propeller torque, twist up the 
leading comer V4"- 

Cover half the wing at a time, cutting the paper with 
about' Vz" to spare all around. Dope spread on the spars 
and ribs with the finger may be used, but it dnes so quickly 
that it is rather difficult to draw the paper smooth. Mu^ 
cilage is somewhat easier to handle. Apply the under side 
first, gluing the edge of the paper to the under side of the 
trailing spar, applying glue to the ribs, and pullmg the paper 
endwise and forward until there are no wrinkles. Bring 
the tissue up around the leading edge and back over the 












































THE ENDURANCE TUBE MONOPLANE 


143 


top, finally turning it under the trailing edge, clipping it, 
and smoothing it down. 

The wing stirrups are bent at right angles in the center, 
as they must span the tube. The ends are bent back at 
slightly sharper angles, finishing in hooks to clasp the wing 
spars. The rear stirrup is shorter than the front, so as to 
give an angle of incidence to the wing of iV". Slip over 
each a 2" length of rubber tubing, to keep the stirrups from 
denting the tube, and cement them to the spars. 

Give the paper one coat of thin dope. 

Now, the propeller. Square the balsa blank, and 3" from 
each end draw a cross line on each face. Draw diagonals 
from the ends. Where these lines cross should be the cen¬ 
ter. Push a pin through this point, and draw lines W 
apart for the sides of the hub. Saw down the diagonals, 
and carve the blades flat, with a thickness of . Camber 
the outsides, and hollow the insides to a thickness of about 
d\". Round the ends, and cut away of the hub thickness 
at the back, tapering nearly to the widest parts of the blades. 
Smooth the hub, sand the blades, and give two coats of 
dope, lightly sanding once more with fine sandpaper. 

With the wing and propeller completed, the next step is 
building the fuselage. Cut the tube stock into two pieces, 
and plane the comers from one face of each, making the 
section of half and octagon. With a gouge hollow the in¬ 
sides of the pieces so that, when they are put together, they 



NOSE CAP HOLLOWING THE TUBE 


































































THE ENDURANCE TUBE MONOPLANE 


145 


have an inside diameter of 1". It will help to make a scrap¬ 
ing template, or pattern, from tin, by cutting a circle of tin 
and nailin g it to a short wooden strip with one edge on the 
diameter. This can be scratched along the hollow until the 
stick slides on the balsa edges, when the proper depth will 
have been reached. Sandpaper the hollow. 

Apply glue to the edges of the pieces, press them to¬ 
gether, and wrap with twine to hold them until dry. Then 
remove the cord and finish rounding the outside, making 
the walls 5 ^" thick. 

Cut two cap pieces PA" long. Whittle their outsides 
roughly to shape, and then hollow them. Remember that 
the finished nose cap fits over the tube, having a shoulder to 
butt against the tube end. So do not carve it too deeply. 
Pin the parts together to try the fit on the tube, and when 
this is good, glue the halves together. 

The tail cap is a plug, with the shoulder outside, and 
the forward end entering the tube. 

Sand the nose cap smooth, give two coats of dope, and 
sand again. Cut the aluminum bearing piece diamond¬ 
shaped, as in the drawing, drilling it to receive the propel¬ 
ler shaft. Bend the tips at right angles, for pressing into the 
nose cap, also cambering the bearing outward a little. No¬ 
tice that the bearing hole is not in the center of the cap, 

but is Vs" below. Cement the bearing in place. 

With the razor blade cut four rectangular notches in 


146 


JUNIOR PLANES 


the flange of the cap. Put the cap in place and glue the 
pieces removed to the tube, fitting in the places where they 
were cut out. When the cap is assembled with the tube, 
pins are thrust through these and the flange parts between, 
for holding the cap rigidly in place. 

For the tail post bend a piece of 3V" piano wire into a 
''U,’’ afterwards bending the ends at right angles. Slit the 
tail plug flange, push the wire post into it, and cement. The 






THE ENDURANCE TUBE MONOPLANE 147 

S'hook for the motor is hooked into the loop. A pin pushed 
through the tube and plug holds the plug in place. 

Bend the hook on the propeller shaft, thrust the other 
end through the cap bearing, string on a celluloid washer, 
a bead, eind another Wcisher, and finally the propeller. Bend 
a hook to press into the hub, and cement. 

In building the stabiliser, draw a plan for the frame, 
as was done with the wing. Miter the leading spars tO' 
gether at the front, and butt the trailing spar between the 
back ends. The three ribs are butted between the front 
and rear spars. When the frame is dry, roll the ribs lightly 
to give a slight camber to them. Cover the frame on the 
under (the cambered) side, and cement the stabiliser um 
der the tube at the rear end, with a 14" block between the 
tube and trailing spar. The best glides are obtained with 
this plane with this positive setting of the stabiliser. 

The rudder, or tail, is square on the lower end, with 
the rib butted over the spar ends. The lower rib butts be' 
tween the spars. Cover the frame on one side with tissue, 
and glue the tail to the top of the tube, and the tail assembly 
is complete. Dope the covering with one coat. 

The landing gear consists merely of a music wire bent 
to fit over the tube, where it is cemented. The lower ends 
are turned out horisontally, forming wheel spindles. 

If ready'made wheels are not used, cut six 1 /s squares 
of balsa, gluing them together in groups of three, with 


148 


JUNIOR PLANES 



the grain of the center ply at right angles to that of the 
outer ones. Drill the centers, and work in cement to harden 
the hubs so that they will not crush against the spindles. 
Mount them, building up lumps of ambroid on the spindle 
ends to prevent them from slipping off. 


Attach the wing to the tube with rubber bands stretched 
from "'V’' to ''V’’ of the stirrups and under the tube. They 
must be tight enough to prevent the wing from swiveling 
around the tube in flight. 

Ten or twelve strands of Vs"' rubber are needed for the 
motor. Rub glycerine on the strands to prevent breakage. 




THE ENDURANCE TUBE MONOPLANE 149 

Install the motor and caps, and adjust the wing forward or 
backward until a good glide is obtained. A nose dive calls 
for the wing being moved forward, and a stall, the reverse. 

Now try a power flight, with the motor about half 
wound. Very likely the ship will stall. If not, wind fully, 
and enjoy a splendid flight. To overcome the stall, do not 
move the wing back, as this will cut down endurance by 
spoiling the glide to earth. Instead, thread a piece of fine 
wire through the cap, from side to side, entering Vs" above 
the propeller shaft. Loop it under the shaft so as to lift the 
hook a little, and pin the ends. If the hook-end of the shaft 
has been raised high enough the plane will gam altitude 
quickly without stalling. If it has been raised too high, it 
v/ill go into a nose dive, or fly with short swoops and re- 
coveries. When just the right position of the shaft has 
been obtained, cement the wire and trim off the extra length. 




























































































































































































































































































































































































PART IV 


BIPLANES 

1 

BUILDING THE BIPLANE CUB 

Talk about climbing! It is more than surprising to see 
the little Biplane, Cub on its first tuned'up flight, for it is 
off with a rush and scoots up at an astonishingly steep an' 
gle, reaching a good elevation before leveling off at cruis' 
ing speed. The tiny plane, for all its good points, is quickly 
and easily built, and very durable. 

For the motor stick have ready a piece of balsa Vs by 
V4 by 8"; for wings, a piece of 3^" balsa veneer IV4 by 12 ", 
cind rice paper 10 by 12 "; for the propeller, a balsa blank 
Vi by Y4 by 6 "; for the bearing, a piece of hard aluminum 
s's by Vs by for shaft, stirrups, landing gear, etc., 20 " 
of music wire; also two small washers, a glass bead, 
ambroid cement, wing dope, and thread. The motor takes 
14 " each of Vs" flat, and i^" square rubber. 

First build the wings. These are flat. Split from the 
iV" veneer two spars wide, and pin them to a board 
2 V 8 " apart, measuring from the outer edges. Then cut iV 
by A" ribs to fit between the spar ends. Put ambroid on 
the ends and the spar edges, and put the ribs in place. Also 
151 


152 JUNIOR PLANES 

fit a rib in the center, and two other ribs centered between 
the end and center ribs. 

When the frame is dry, 
block up the leading left 
corner Vs', coat the upper 
side of the balsa with thin 
ambroid, and stretch paper 
smoothly over it. Trim to 
the wood with a ra2;or 
blade, and dope. 

Carefully cut the wing on the under side of the center 
rib, spars and all, and bend the wing until the tips rise 2" 
above the center. Fill the cuts with ambroid, and let dry. 

The lower wing is built in the same way, but it is only 
1 % by 9 ". The dihedral is made to fit the upper wing. Like 
the upper wing, its end corners are clipped off, for neatness 
and to reduce air resistance. 

The stabilizer is IVs by 5^4", with the ends mitered. 
Use balsa by Vs' for the spars and ribs. Only three ribs 
are needed—the center rib, and the two ends. They are 
also flat. Cover the upper side with rice paper, and dope. 

In making the motor stick, taper the under edge from 
the center toward the ends, where it is i:\" wide. Miter 
the leading end, as shown in the drawing, and sand the cop 
ners round. 

For the bearing drill a small hole Vs" from one end of 




BUILDING THE BIPLANE CUB 


153 


the aluminum strip. Bend it twice, as shown, so that the 
end with the hole will be nearly vertical when the bearing 
is mounted on the motor stick. Cement it to the upper edge 
at the front end, bind with thread, and cement again. 

Ambroid the stabiliser beneath the rear end of the stick. 



the leading edge lapping about . It should be about 
parallel with the center of the stick. 

For the tail skid cut a 214" piece of music wire. Bend 
the lower end into the skid. 

Now build the tail. On a board draw a rectangle F /4 
by 4". Measure 2y4" along one side, and 2y4" along the other 
side from an opposite comer. This gives the angle of the 
ends. Lay down the front and leading edges of by Vs" 






















154 


JUNIOR PLANES 


balsa, fitting the ribs between. Cement the joints, and when 
dry, cover with paper, and dope. Clip the sharp ends. 
Ambroid the tail to the back end of the stick. 

The lower wing is held to the stick with the usual clips 
or stirrups bent from music wire. They must fit snugly 
around the stick. The legs of the front stirrup are Vi' long, 
while those of the rear stirrup are The ends of the wire, 
before clipping, are bent back \ so that the points can 
be pushed into the spar edges. Cement them. 

The upper wing is held above the lower with struts. 
Cut two pieces of balsa Vi by 2", and shape in the edges to 
give a width of Cement these to the ribs, as shown, 

forward of the upper trailing edge, and Vi' behind the 
lower leading edge, staggering the wings. Be sure to have 
the upper center over the lower center, with the wings 
parallel to each other. 

The landing gear consists of a piece of music wire 8" 
long bent into a clip at the center to fit the motor stick 
behind the front end, where it is cemented. Spread the 
ends about lVi \ and bend the ends out \ forming axles 
for the wheels. 

The wheels are in diameter, cut from tg" balsa. 
Cement them to the landing struts, since it is not necessary 
that they turn. Remember to have the lower edges closer 
together than the upper edges, for the weight of the 
plane when it is standing on the ground, forces the struts 


BUILDING THE BIPLANE CUB 




apart and will bring the wheels parallel to each other. 

Smooth the propeller blank, measure IV 2 ” from each 
end on both faces, and draw diagonals from these points. 
If accurately done, they will cross at the center. Draw 
parallel lines Vs" apart for the hub, stopping where they 
meet the diagonals. Cut along the diagonals, and carve the 



backs of the blades, making them slightly hollow. Aften 
wards curve the fronts, round the ends of the blades and 
other comers, and taper the blades toward the hub from 
the back, removing Vs" of wood. Pierce the shaft hole with 
a pin, sand the propeller smooth, with the blades about Vs" 
thick at the centers, and it is ready to install. 

Cut the propeller shaft 2 V 4 " long. Bend a rubber hook 































































































THE N'STRUT BIPLANE 


157 


on one end, and push the other end through the propeller 
hub. Bend a hook on this end, and push the other end 
through the prop hub. Slip a washer, a bead, and another 
washer over the shaft, and put it through the bearing. 

For the motor use a loop of Vs" flat rubber and one of 
i/' square. Make the loops about Ys" longer than the dis' 
tance between hooks. 

Adjust the plane by moving the wings backward or 
forward until a good gliding position is found, and it is 
ready for flight. 

2 

THE N'STRUT BIPLANE 

The N-Strut Biplane, while not a long flier, is a fast 
climber and good performer, and is one of the easiest models 
to build that has been described in this book. 

These materials are needed: Balsa, one piece by 1V% 
by 16"; for propeller, one piece % by 1 by 6"; music wire 

in diameter, 19"; aluminum wire, iV" in diameter, 8"; 
rice paper, 6 by 20"; two celluloid wheels Ya" in diameter 
(balsa wheels may be used instead); ambroid cement, wing 
dope, two celluloid washers, one glass bead, pins, and thread. 
Three strands of Vs" flat rubber—about 2 ft.—are needed 
for the motor. 

First build the wings. Both are alike, being iVi by I 2 V 2 ". 
Cut the spars to width and length and pin them in position 


158 


JUNIOR PLANES 


over a plan drawn on a board. Butt the five ribs between 
the spars and clip off the comers. The wings are better if 
the edges are sanded rounding. Cover them on one side 
with rice paper, painting them with thin dope to stretch 
them tight. Cut halfiway through the centers of the spars 
with a ra 2 ;or blade, and bend them there to form the dihedral 
angle. Cement, and block in position to dry, at the same 
time giving a slight upward twist to the front edge of the 
left wing to overcome propeller torque. 

The stabilizer is built in the same way except that a 
"‘'V” is made in the trailing edge at the center. 

Cut the motor stick to dimensions, sand smooth, and 
round off the comers. Cement the stabilizer underneath, 
projecting about Vi" behind. A pin thmst through the cen- 
ter rib into the motor stick and bent up at the end serves 
as a tail skid. 

The tail or mdder frame is aluminum wire with the 
lower end of the leading edge pushed into the upper edge 
of the motor stick, while the curved trailing edge is forced 
into the rear end of the motor stick just above the stabilizer. 
Add a little cement, and cover one side with rice paper. 

Drill the aluminum bearing for the propeller shaft and 
bend it almost at right angles to itself before binding and 
cementing it to the forward end of the motor stick. 

The stirmps are ^ 2 " music wire bent into “U’s” in the 
centers to clasp firmly around the motor stick. The ends, 


THE N-STRUT BIPLANE 


159 


bent at right angles, fit underneath the lower-wing spars. 
To give an angle of incidence to the wings the rear stirrup 
should be about Va" higher than the front. Cement these 
to the under wing. Put the upper wing in place by cement¬ 
ing four struts iVi" long between the two wings. These are 



placed about half-way between the two outer ribs of each 
end, and the wings are staggered by pressing the upper 
forward Vs" ahead of the lower. A diagonal strut between 
each pair completes the ends. Cement two diagonal struts 
from the lower wing, meeting at the center of the upper. 




















































160 


JUNIOR PLANES 


The landing gear is bent from music wire, forming a 
''U'** to clasp the motor stick just behind the bearing. For 
wheels, glue together two tV' thicknesses of balsa with the 
grain at right angles, or use celluloid wheels. Bend the wire 
struts at the lower ends to form hori2;ontal spindles, and 
cement the wheels on these by means of blocks on the tips 
of the spindles. 

The propeller is carved from a straight-grained balsa 
block Vs by 1 by 6 ". Sand it smooth. Bend the hook on 
the propeller shaft and push it into the hub, securing it to 
the propeller by means of a hook made in front and pressed 
into the wood. A glass bead between two celluloid washers 
is used for a thrust bearing. 

Make a tail hook of a pin, bending the head at right 
angles and pressing this into the motor stick just ahead of 
the tail, where it is cemented. 

When the plane is assembled with the wings about half- 
way between propeller and stabili2;er, try it for gliding. If 
it nosedives, move the wings forward; if it stalls, move them 
backward. When a good gliding adjustment has been found 
try it under power. If it stalls, bend the bearing a little 
more downward. If you have much trouble in getting a 
good flight try loosening the leading edge of the stabili2;er, 
cementing a sV' or thick balsa block between it and the 
motor stick. It will then be necessary, of course, to readjust 
the position of the wings. 




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